I am tired of hearing this question. It is really starting to aggravate me hearing folks whine about how much better the UK versions of TV shows are and how the US "always" manages to screw up UK shows by making their own versions.
It simply isn't true. Granted, recently there have been some pretty awful adaptations of UK shows. Life on Mars springs immediately to mind. But who would argue that The Office (which has run more than twice as long as the UK version with more than twice as many episodes per season I might add) is worse than the UK-aired version?
Who, would argue that Steptoe and Son is worse than Sanford and Son or that All in the Family is inferior to Till Death Do us Part? Humor is fundamentally cultural, so there are real arguments to be made for both Three's Company vs Man About The House. The simple truth is that some fine US versions of UK shows have been made.
But the real question is why aren't they airing the UK versions, not why are the remaking them for US audiences. There are three very good reasons WHY (say that last word with a whiney plaintitive voice to get the way I always hear it from people):
Money: If you take something from another country and air it here, you have to renegotiate the money to the original actors, writers, producers, and in some cases, the country itself (the BBC is a government agency). This means that you make less money than you would than if you licence the concept from the creators. The creators (not the BBC) own the creative property. If they are willing to sell, then you pay once and then you keep all the rest of the money it makes. Doing it the other way you make a lot less and can't use Hollywood accounting.
Distribution: In most cases if the other version is popular then it is being shipped tocountries all over the world. The UK shiips programs to Canada, Australia and New Zealand becasue their national broadcasting agencies are affiliated with the BBC. BBCAmerica is a private corporation which can licence properties from the BBC at a fixed rate, but they STILL pay. And for popular shows it isn't cheap. If another US network wants it they have to outbid BBCAmerica. If BBCAmerica wants to up the ante, the other network is out of luck. So from the get-go there is a minimum deal that will have to be made. For a cable network that isn't always economical.
Secondly if the show is airing simultaneous in the US and the UK, the US will almost certainly have to have it delayed (two weeks for Doctor Who) so the UK is forced to get it from the BBC. This is so the BBC can justify its annual TV Licence to the Brits. If they could download or stream it (you know they will) for free, then they would have a hard time justifying paying for it. This is why HBO will never buy a UK show. Never.
Market: UK shows are not sold by "seasons". They are sold by "series". A Series can be anywhere from 3 to 15 episodes (and even that isn't consistent). It is sold as a whole self-contained show. It is produced and then aired. If it is popular, the BBC commissions another series. They specify how much they are willing to pay and the producers tell the BBC how many episodes they can produce for that amount.
One of my favorite UK shows, The IT Crowd, has 6 episodes per series. Another favorite, The Thick of It, had 3 episodes for the first two series, 3 stand-alone specials, a feature film, then 8 episodes for the third series. American TV can't deal with that kind of schedule. Coincidentally, a US version of The Thick of It hasn't been picked up by ABC or HBO.
Our current system uses two seasons (Fall and Spring) of 26 weeks each. Most TV shows produce 22-25 episodes per season and then air once per year. Some networks are experimenting with half-seasons of 13 episodes aired once or twice a year as a way to control expenses. But without at least 13 episodes "in the can" per series/season the system can't sustain itself. US Advertisers aren't willing to pay for only 6-8 shows of exposure.
SO. There it is. Those are the reasons. And now that you know you aren't going to stop complaining are you? What you really want is more UK episodes. Or you want US producers and writers who "get it" better than they have. Or you want the US to produce some original content for a change. Please, for the sake of my peace of mind, if you wish to complain , compain about the right thing.