We see the same here:
“My observation is the opposite: I see Amazon and UPS all the time, but rarely see FedEX.”
Fed Ex has an expensive delivery before or shortly after 8:30 am.
Then, they have afternoon deliveries with drivers, who often can’t read the address labels correctly.
UPS uses the postal service delivery for Costco and Amazon? with our mailbox getting the delivery.
We encountered a similar problem. Our house numbers are in cursive, and until lately, we have never had an issue with that. However, now we have had to replace them with numerals, because even the post office returns mail to us marked as "No Such Address", simply because the postman, like many of the delivery drivers, cannot read cursive.