I think you need to research this a little more before you decide who to direct your rage at.
Central Government gives each Council a target housing number that they have to provide within a certain period, this is called a 5 year housing land supply.
Councils then have to look at all available land, figure out how many houses can go there, and see if they can reach that housing number. They look at things like brownfield land first, and areas of green belt as an absolute last resort if they categorically cannot fit this number anywhere else.
If a Council doesn't provide the set number, they are unable to adopt a development plan, which leaves them with very little power to refuse any housing developments, anywhere, in completely unsuitable locations.
Essentially, Councils are left with a choice of selecting a very carefully chosen area of Green Belt for housing, or having no planning policies and leaving every other area of land in the entire district open for development.
Things like highways, school places etc are carefully calculated, and while things might get tighter, you cannot get planning permission if there is not enough school places, or highway capacity. Developers are either taxed to contribute towards these things, or have to provide them within the development.
Short version: Councils don't just build on Green Belt land willy nilly.