We had the same problem. We pay the bills online when we receive them, but in the last year the PO didn’t deliver an Exxon bill and an AT&T bill. They didn’t get paid. Got an extremely thuggish nastygram from Exxon.
I figure someone else got our bills ‘cause we get other people’s mail all the time. One day, I was sticking an incorrect envelope in the slot with “please re-deliver; sent to wrong address” written on it. The mail lady was there and SHE yelled at ME because what I had writtn would get her into trouble.
There are procdures in place to "recover" from such losses.
Now tell me, do you think the employees at the phone company give a damned? What about their contractors?
If it weren't for postal audit procedures a lot of that sort of thing would be "swept under the line" and forgotten.