It’s decided main by a rules based system. Companies are better at navigating that system, locals who invariably object (a tiny minority) just whine about things that aren’t relevant. These rules are created by local councils and driven from things like local plans which are approved by local residents in local referendums. I’ve seen residents approving the local plan saying “houses should be built in this area” and then 6 months later start protesting about a development in that very area.

If they want to change planning they can elect a government to change the rules to a “don’t build anything” system. Fortunatly the population as a whole doesn’t do that.