Why does British TV only shoot six episodes of each show a year versus the US where you shoot around 24 a year?
Most British TV series have one writer; two is not uncommon, but more is unusual for a sitcom. This produces consistency, originality and individual style, but like the Ferrari cannot be mass-produced. It also allows more time for reharsal and shooting - not a great deal more, but enough to allow original ideas to develop.
The different model employed in the UK also allows actors and other talent to work on more than one programme at the same time, too. A writer may write the episodes for a series of one sitcom, then while it's being produced, write episodes for a completely different show. The same is true of actors--many prominent actors have had successful shows running at or near the same time for several years. And the series (or season) of a single programme aren't necessarily limited to one per calendar year. If a show is very successful and all the ingredients are available, a second series can go almost immediately into production. On the other hand, unavailable writers or actors can be the reason a programme doesn't air new episodes for a longer time.
The shows that are bought in the US are often only 6 episodes, but many shows run for 13 weeks or longer and of course we also have soap operas and dramas which run continuously maybe once a week or 3-4 times a week.
We also have one two daily shows but most of the ones shown are from Australia.
The reasons are partly financial and partly historical. On average, budgets for American TV shows are - and have always been - much higher in comparison to their British counterparts (although for news, documentaries and general entertainment shows they are comparable).
This is for a variety of reasons, but primarily due to a.) the size of the American networks and their parent corporations, b.) the larger amounts of advertising revenue generated in the US market, and c.) greater revenue from overseas sales and syndication (a concept that doesn't really exist in the UK). So generally speaking, British networks arrived at the model of usually having just one or two writers for series, and not having very long seasons, because it is cheaper that way. This doesn't mean that all seasons are short - as noted above there are prime time 'soap operas' that are on year-round, for example - but as a general rule, British seasons tend to be from 6 to 13 episodes in length.
The BBC is a special case, as it generates 100% of its income for programme making from something called the license fee, which is an annual charge that anyone who owns a TV in Britain must pay. Although the license fee is collected and spent independently from government, the BBC is forbidden by law to use any money from its commercial activities (merchandising etc) for programme making, as this would be seen as creating an unfair advantage over its commercial rivals. American readers might find it helpful to think of the BBC as like PBS, but with compulsory subscription from everybody. The result of this is that the money available to the BBC for making programmes is fixed year on year. This has the duel effect of making it, in theory, freer creatively (because they don't have to sell advertising) but tighter with budgets (because they can't spend any more than they get from the license fee).
The other reason is to do with changes in the way programmes are made. In the 1960s and 70s, seasons of British drama often ran to the same length as they did in America, but whereas American shows were usually more 'glossy' in terms of production values, British audiences were generally more accepting of a cheaper, less 'cinematic' look (for example, using videotape instead of film). As that changed through the 80s and 90s, and expectations increased, so the British networks were forced to produce shorter seasons in order to put more money into production budgets.
It is also worth noting that some people prefer short seasons on a creative level, as it is easier to have a single story arc running through the whole series without having to create too many conflicting subplots, or stringing out the resolution for too long. It is interesting to compare the US and British versions of 'the Office' in this sense, for example.