If recipients of packages were the customer, fedex would already be losing. But it is the shipper, not the recipient who is the customer of fedex. And as long as the shipper can blame fedex, as saves money, and the shipper isn't yet losing customers due to shipping, service doesn't matter.
But if recipients had a say in the delivery company, I would bet that by a large amount, for parcels that ground/HD deliver, the recipients would choose UPS or USPS if given a choice. You never know from day to day if your ground package is going to be delivered or not if fedex is delivering it. For example, simply because a shipper decided to use fedex HD instead of UPS, USPS, or even Fedex Ground, I have to wait 2-3 more days to get my package. It would have been delivered Saturday if it was USPS, but I won't get it until Tuesday at the earliest IF the HD driver decides to stop in my city. He appears to be on an 'alternate' day delivery, with service to half the county each day. With tracking, I can see 'package on vehicle' or 'out for delivery' and then coded as not delivered for customer not home, or some other bogus reason, sometimes scanned as not delivered as early as 2 pm.
I have actually begun to look at the carrier if the item I need is available from multiple sources, and the seller using fedex offers NO advantage.