I am volunteering in an housing rights organization in France, and I am and have been tenant in a city with high price and housing shortage.
There will always be many people taking "illegal deal" as sometime you have no other other solution, or other solution are even worse. And many many landlords are doing illegal things, including public housing.
Tenant don't have the same bargaining power / freedom / agency than landlord. Fighting illegal stuff that do landlord is long (usually longer than kicking out a squatter) and difficult. And you have little incentive to do it as a tenant : being in a fight with your landlord = being sure to have problem down the line
My feeling is that your comment ignores this asymmetry.
There will always be many people taking "illegal deal" as sometime you have no other other solution, or other solution are even worse. And many many landlords are doing illegal things, including public housing.
Tenant don't have the same bargaining power / freedom / agency than landlord. Fighting illegal stuff that do landlord is long (usually longer than kicking out a squatter) and difficult. And you have little incentive to do it as a tenant : being in a fight with your landlord = being sure to have problem down the line
My feeling is that your comment ignores this asymmetry.