Law enforcement monitoring the mails?

Factual Questions
1

Let’s say, hypothetical like, that you live in a US state where sex toys are illegal (state law, not fed). Does state or local law enforcement have the right or ability to examine shipments coming into the state, through US mail, UPS, or Fedex, match it with known sex-toy shippers, and bust you for presumably ordering it? If they have this ability, is it common for them to do this?

This is a hypothetical situation, mind you, not really about sex toys but regarding a product that happens to be illegal in a handful of states and the manufacturers are few and presumably well-known.

2

This isn’t much help, but I notice signs all the time saying that any postal employee can open any media mail package to verify its contents.

3

I believe UPS will do it periodically on packages going into dry states/counties.

4

For what it’s worth, here is what the USPS says. I guess if you don’t want your package opened, you should send if first class or priority mail.