You are presenting twisted view of the election process.
1. after four years of trump chaos it's no surprise we had huge turnout to get rid of him- we also have more voters available than those past elections- the population grew.
2. I don't know what state you live in but absentee mail-in ballots are tracked - yes somebody could have picked up yours and filled out and sent it in. But in Michigan you don't get a mail in ballot unless you request it and then you are expecting it- if you never get it you report it to your clerk- should they find it was sent in they can void it and give you another. It is not possible to both fill out a mail in ballot and vote in person either.
3. Your eligibility to vote (at least in Michigan) was already verified by ID when you registered - no need to do so again with mail in ballot- sending ID in the mail as you suggest opens up the prospect of ID theft- and as to false voting see #2
As to PA you are presenting rightwing tropes regarding the ballots- so the ballot was left on the steps or the mailbox- that is the mail works.. nothing nefarious
As usual- someone complaining about voter fraud that doesn't UNDERSTAND THE PROCESS which makes the election secure- jeezuz you LIVE in PA and don't bother to understand your own system?
Helpful link below- it sounds like PA has a similar system to Michigan which is secure
