We once ordered something when we lived in Houston - only to find the order envelope and form lying in the street sans check a few hours later. We changed our account number and so forth because with a good scanner and printer you can make a very realistic signed blank check from a filled out one.
So now if we use the USPS to send a check we always put the envelope in a locked mailbox controlled by the USPS.
We try never to send those.
I don’t trust people. My mail goes into a locked box here on the property, in a locked building or at the drop slot in the post office. Thirty years in Vegas has left me rather cynical.