When it comes to TV, us Brits get very defensive when America tries to adapt one of our shows - just look at the reaction to the announcement that Black Mirror is getting a US remake. There's a good reason for the concern though: Most of the time these adaptations don't really work... and that's actually a good thing.
Although some ideas have made it across the Atlantic and succeeded — The Office, for example, is arguably the biggest one — but more often than not it doesn't really work out. Adaptations of high profile shows like Skins or Life on Mars flopped big time despite being big hits over here, and the announcement of another (see, for example, the largely pointless remake of Luther, or David Finchers' take on the smashing Channel 4 series Utopia) usually draws a lot of gripes. (And then there are the repeated attempts to remake The IT Crowd Stateside.)
Some of that is a bit of patriotic bluster — of course you yanks can't do it as good as us — but it's also usually because Television is very much a product of the nation it was created in. Not just the content, but the look and feel and tone of it. They're made for the home audience, not anyone else, so it's jarring to see those ideas suddenly transplanted elsewhere and taken out of their original context.
American TV also has a lot of money thrown at it, too, whereas even today British TV is still made on the modern equivalent of a shoestring budget and some gaffer tape in comparison, something which definitely impacts on creativity in different ways — American TV can afford to go big and grand on a scale British TV simply can't, while arguably British shows thrive on the sort of pressure to make quality with less. There's a reason why the import and export of TV between the two of us is met with open arms in comparison to the cold shoulder adaptations usually get — it means we're witnessing the TV in its original context, coming at it from a different place of understanding. We appreciate that it is something different to what we would usually have, rather than a 'foreign' idea twisted and changed to fit in with what we have got already.
But it's not just a question of necessarily tone, scale or even social context that makes these adaptations falter — it goes much deeper than that, and applies to all Television, not just science fiction or fantasy. The way Television is fundamentally set up in both the US and the UK leaves an indelible mark on the media each country creates, and it's the absence of that mark in an adaptation that usually ends up crippling it. By taking it out of the environment that birthed it, it loses a certain spark that is otherwise almost impossible to recognise.
The kind of simple way to say this is 'It's basically the BBC'. Unlike the US, British media is heavily focused on Public Broadcasting services - everyone has to pay the license fee to be able to watch a television, and it's always been that way. Public broadcasting essentially has a monopoly on mainstream British television, supported by money from the public rather than advertising.
In America, it's completely different: Networks are for-profit, and public broadcasters don't really offer competition to those gigantic companies because the focus from the audience isn't there. Our Television industry is built not around advertisement, but essentially the trust of the Public, as the Public are funding most of it.
British broadcasters that don't receive public funding (like ITV — Channels 4 and 5 receive some public funds but not anywhere near as much as the BBC) are competing with an organisation that prides itself on having a reputation, on producing quality television, rather than competing on profit margins as it is in the US. In the UK, everyone's competing with the BBC - not for profit, but for the perception of producing quality.
This is not me being snooty and saying that the British way is better than the American, or visa versa — they're both completely valid approaches to making TV. But it highlights a key fundamental difference in our approaches to TV that influence our countries respective programs.
This plays a role in the fact that British seasons are so much shorter than American ones (the BBC doesn't need to pad out a series to sell airtime for advertisement — so it means you get tighter, shorter runs for drama), or why there can be huge gaps between series of a show such as Sherlock (if the creator doesn't have a story to tell, the show can wait, because once again, there's less of an incentive to be selling airtime — because you're competing with the BBC, who can't make a profit selling airtime). That wouldn't work in America, where having a big series that you can sell advertising time during is of huge benefit to the network.
A similar circumstance is why you see 'mid-season shows' in the US like the relationship between Agent Carter and Agents of SHIELD — to give creators time to actually shoot these massive, 22+ episode seasons and yet not actually sacrifice losing out on airtime money in those slots. Nothing like that exists here in the UK, because when one Drama series ends after a couple of episodes, you just start up another show.
There's no real impetus to create a huge series — which is where American shows shine because sure, there might be some filler, but it gives story arcs and characters room to grow and develop over a much wider timespan, or for a series to focus on multiple story arcs in progression. Here in the UK everything is much more compact, because you're telling your story over 6-10 episodes, rather than double the amount. They're two radically different approaches to drama with their own strengths and weaknesses — but they're also why an idea created for British TV doesn't necessarily work out when transposed into the American broadcasting format. Would a series like Black Mirror — a short, intense and laser-focused jolt of a programme — be so effective if it was told over 13, 15, 20 episodes, rather than three?
And it's not just on the macro-scale of whole series that this idea has an impact, but even right down to the pacing of individual episodes. British programmes aren't really built around a series of cliffhangers for going into ad-breaks, because not every broadcaster has ad breaks during a show. When a British series caters to the American audience by adopting their format, sometimes it doesn't necessarily work out well — the modern Doctor Who is a case in point, with its 45-minute episode format that is designed to integrate well with the American style of '1 hour slot = 40 minutes programming, 20 minutes ad breaks'. It's a completely alien format here in the UK though, where if it were made with solely the UK audience in mind it would probably be 60 minutes long — hence the frequent criticism that some Who stories feel as though they're trying to cram to many ideas into too short a episode.
Ultimately though, these differences are what make our countries' respective science fiction programs so great in the first place. The very different circumstances mean that instead of just cribbing off each other and producing similar media, we get to participate in a unique cultural exchange: The import and export of content that has variety, its own heart and soul. It's way better that we recognise that we're both different, and celebrate that, instead of cribbing each other's ideas and trying to make them fit in an environment they don't, and can't.