pretty sure no one said mice and rats live in everyone's buildings, but that they are especially common in old buildings in cities with high density of population (i wrote such a comment myself). and just because they appear does not mean they have to stay: people do call pest control teams or, in regions where vermin that appear in an appartment are the problem of management and not of the owner, they call maintenance.

the entire argument of this thread is that while being slovenly can help perpetuate or exacerbate a rodent problem, it's typically not going to create it. rodents get in because there are or they make holes in the floors or walls, and they are usually drawn to heat.