It's an illegal operation. Under that sort of restriction, any building occupied would either need to be occupied by the registered owner or have a registered lease. If those aren't found, the people are evicted. The point is to ensure that everyone knows that you need to have a registered document to stay somewhere so nobody takes those deals. Then on the landlord side, you need to enforce substantial fines for any that have offered unofficial leases and surveillance for property owners that have repeat offenses - both to protect the owner from repeated squating and also to catch any owner bypassing the law.
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.
"My feeling is that your comment ignores this asymmetry."
These are enforcement problems, not squatter problems. As you've said, the things the landlords are doing are already illegal. In the US we have Attorney General offices that will handle housing cases on behalf of tenants.
Both parties can benefit from better enforcement and written and recorded leases. Penalties for landlords leasing without recorded agreements may be more easily enforced that under the current system.
This asymmetry makes enforcement easier when it profits the landlord, and make enforcement more difficult when it benefits the tenant... Your reflection seems based on the idea that there is a symmetry on the enforcement
I appreciate your response. I feel the same as the other commenter: the asymmetry between "a steep fine" and "losing your home" is enormous. But "what happens if the fine is enormous" (say, the landlord also stands to lose their home) is an interesting thought experiment - how big does the punishment need to be to "fix" the power imbalance?
That's not really a functional asymmetry. All you need is to pass a minimal threshold to disincentivize the behavior. A fine that outweighs potential illegal rent performs that task.
It also depends on what you mean by losing one's home. That's not an issue for people who would sign the written agreements. Afain, we want a disincentive to informal agreements, including from renters and squatters. I'm not sure how you can equate loss of ownership with loss of temporary use.
In England, if no contract exists but rent is being paid a tenant has quite alot of implied rights in law. Though enforcement of these rights would normally fall to larger organisations such as charities or councils rather than individual tenants. I remember a news story where a landlord was accepting casual rent for beds in sheds in the garden of a rented property who was brought to justice because the sheds were not habitable buildings.