The idea (although rather poorly implemented in the UK state system) is that choice leads to competition, and competition leads to improvement even of those at the bottom (and even for those who don’t really pay attention to the choice/don’t care). It’s a market philosophy of sorts.
I know that's the idea. The result is schools spending a non trivial amount of time jumping through hoops for the benefit of people who are ill equipped to evaluate those schools. On top of that the number of places are fairly static year to year so all schools end up getting filled anyway, but the 'better' schools are filled with the students that arguably least need the benefits, whereas the worst schools are filled with the children of the least able.
Yes. The 'market' mechanism for popular schools to find money and permission to expand while less popular ones are closed or taken over is missing and subject to too much political interference. So it arguably ends up as the worst of both worlds.
