Reinforced concrete walls don’t keep out noise on courtyards and also don’t work as the decibels get higher and higher. Another major nuisance is the constant sound of sirens (often at night), or domestic disturbances spilling into hallways - the front door isn’t a reinforced concrete door.

People who value peace and quiet will select places to live where the neighbours don’t engage in domestic violence or otherwise do things that result in the police coming out with sirens going.

Right, so that sort of thing needs to be part of whatever proposed solution to the housing problem. This will of course raise building costs etc., and the regulations will need to have teeth so people can't just build apartments out of cardboard and paint them concrete-color. Also, that concrete will need to be really thick to ward out subwoofer noises. Maybe you could get around this by banning subwoofers.