I’ve shipped many a usps money order and I’ve had one tracked money order bounce around to and from a Georgia sort facility unexplained and a MO sent to me that did the same thing. Otherwise, it’s been reliable for me and still a good way to go for the cost.
Most everyday, I receive parts for my job shipped FedEx overnight. Excluding weather related delays, they’ve been good. On rare occasion, a box will not make a FedEx flight. It can be frustrating and even weird when one box makes it and another identical box doesn’t and they left the same place together.
Usps has a very useful tracking tool now with packages and everyday mail. I receive an email at 7:05am very morning with a scan photo of each piece of mail being delivered to my box that day. Also, once usps receives tracking for packages, i can track it myself and know what day the package will deliver. The scan for letter mail is done at the sort facility so I know same day if a piece of mail is missing when I get home and check mailbox.
USPS has an app for it, and on their app and website it’s called Informed Delivery. Easy to sign up and it’s free.