New tenants have to pay market rate to begin renting. Rent control kicks in after that and prevents the rent from increasing much. If the other renters had bee

New tenants have to pay market rate to begin renting. Rent control kicks in after that and prevents the rent from increasing much. If the other renters had been there for many years, they'd still be paying market rate (plus a bit) from years earlier. That could be a lot less than market rate now. That's why renters in rent-controlled units tend not to move as much - as market rates go up, your rent gets relatively cheaper over time and that's an incentive to stay put.