Some cities have this nice feature where there are enough studio and 1-bedroom apartments available in low-rise and mid-rise apartment buildings that all the people who want to live in small apartments can afford to, pushing down pricing of all housing including the 4-bedroom single-family houses, and the duplexes, etc.

Other cities are zoned to only allow single-family houses on most of their lots, and don’t have enough small apartments, so instead all of the people who want to live in studio apartments end up stuck splitting the rent 3 ways so they can afford to sleep in the dining room of what used to be a single-family house. Due to rent control people living with roommates get locked into their slightly awkward housing situations, and can’t afford to move in with a partner, trade up for a larger space to start a family, or even move when they have a falling out with the roommates. Now the rent price of single family houses goes up to whatever 3 or 4 full-time junior programmer salaries can pay for, all of the families with parents working less lucrative careers can no longer afford the city, and only the richest can afford to ever buy houses.