Earlier quoted context omitted.
How does germany deal with the crazy tenant that destroys the place but still pays their rent? Is it an expensive and long drawn out process involving eviction court or is the security deposit very substantial?
Can be hard to fight for a landlord. Since tenancy is a very asymmetric contract (since one party's livelihood depends on having a home and the other party is merely inconvenienced if there's no tenant), tenants have vastly more rights than landlords. Terminating a contract can be done if the tenant is behind at least two monthly rents in payments, or if the landlord has personal interest in the property (Eigenbedarf…
Elderly people who are renting out a spare unit usually can't afford large amounts of damages or court fees. Also if your mortgaged backed it can be fairly financially ruinous while your waiting for repairs to be done and you have no rental income. People who also ruin places tend to be judgement proof too.
I'm guessing Germany is more civilized than SF, so these worries are not as high, but I suspect it's part of the reason why places like berlin have supply issue despite a %5 vacancy rate in some buildings.