Why can’t the uk government just build like 400k annually council houses rather than relying on private companies who are just focused on profits?

The labour government wants to build 1.5 million “affordable” homes predominantly relying on private companies.

Why can’t the uk government just build massive amounts of council houses which will truly help ordinary people have an affordable secure housing, end right to buy immediately.

Please don’t say “we don’t have the money” the uk is one of the richest countries in the world, there should be no homeless people, children in poverty due to living in dire circumstances like emergency temporality accommodation etc.

The post ww2 government had that idea why can’t this government implement it again?