The Local Planners are constrained by government diktats. They are told they have to allocate land for a given number of properties and if they do not do it pdq, they are constrained to grant planning permission to any developer who puts a planning application in until that number of properties is reached. If they refuse the developer goes to appeal, and will usual get consent on appeal. It costs the councils money to fight appeals they know they will lose so why go to the expense? It is easier and cheaper just to grant planning permission at the start.
Councils are not allowed to take into account the lack of physical infrastructure, drains ,sewage, roads, schools, health services or any of the other services now essential for modern living. They do not have the money to put them in and often the services, like roads and health services are provided by central government, not local government.
I absolutely accept that there is a dire housing shortage at the moment and I am not a NIMBY, I do accept that some of that housing is going to be in my back yard, but the way that developers can overrule councils and councils overrule the preferences of local people who are willing to, and have, identified suitable readily accessible land for building sometimes reduces me to tears of impotent rage.