How do kidnappers hide people so long?

How do so many people get away with kidnapping others and keeping them?

I can’t imagine it because I’m not a psychopath, but wouldn’t you have packages delivered, neighbors stop by, family events, etc…to interfere with your victims?

I don’t know some of my neighbors, and I guess it’s possible one of them could harbor a person in their basement, so what would we look for?