They already have an incentive to fix. In the UK they're legally obligated to and tenants can take them to Small Claims Court if they don't.

Periodic (rolling) tenancies can be ended with two-month's notice, so the landlord might decide to evict rather than repair. With longer tenancy agreements, the landlord can't evict until the tenancy expires, and so tenants can use their legal rights to compel the landlord to make repairs.

In short, the landlord can't kick people out as an alternative to spending money on repairs.