Why are names crossed out on my Junk Mail?

I moved into an apartment recently and when I check the mail, there is junk mail that was addressed to the former tenant. However, that tenants name is crossed out with an ink pen. I've noticed this on a large variety of the junk mail I receive. How do the junk mailers even know there is a new person here? Or is someone going through and tampering with my mail? I live in a relatively small town. Thanks.