And there are people who do not have your trust in the postal system or the election process itself. The longer voting is allowed the more games can be played. I've heard stories from people with political ties about helping elderly people vote and then when they brought the ballots in, removing certain ballots because they knew who the elderly person posted for. These stories may be 60-70 years old, but I'm not as bullish as you that the system is clean.
Whether or not you voted is public record. I dropped my ballot off yesterday and it was received today. Things like ballots not being delivered could be caught easily and we will always be susceptible to that type of risk since at some point in your life, standing in line to vote won't be an option for you.
If you don't trust the postal system, drop it off at a ballot box yourself.
If you don't trust mail in ballots in general, vote in person early.
If you don't trust early voting, show up on election day.
Lots of options for any trust issues you may have.
