I've only had USPS fail a few times.

Once they broke a fragile things, which. Understandable. Luckily it wasn't unreplaceable or anything.

Second was shipping a perishable to a person. That person didn't upkeep their p.o box! That perishable returned after...an extremely long time. I did not open the box. I did not want to see.

I've shipped a lot over the years and been shipped a lot, and I greatly prefer USPS over other options.