charlesz
The developer documentation for UPS is thousands of pages long. The document explaining how to quote a domestic shipment is over 600. I don't have them in front of me right now, but FedEx is the same. You can't even integrate directly with USPS anymore. You have to go through someone like Stamps.com, Endicia (which are now one and the same), etc.
We only ship 200-300 packages daily, but there are benefits in using multiple carriers. For one, small lightweight and low-value packages always go USPS. Flat rate boxes are free and easy to use. Between the two big private guys, using multiple carriers gives you a negotiating advantage. Our reps probably visit us twice a month to try and keep on our good side.
Our ERP can calculate the best value and delivery time for a given order. For example, taking advantage of the FedEx Express OneRate program for a given package might a) reduce our net cost because the boxes are provided to us for free and b) get there 2-3 days faster for a buck more versus UPS Ground. And we can pack 50 pounds into that Express box under the OneRate program.
Stocking supplies isn't too terribly hard. We probably have 20 box sizes we use, plus FedEx and UPS small/medium/large vendor-supplied boxes and a few USPS sizes. Takes up a surprisingly small amount of space.
I'm still longing for the day that Shippo is fully fleshed out so I can offload that massive infrastructure headache off to someone else.
Maybe I'm the odd one out, but I don't need any glitz and glam in my email client. I just want it to work and show me the email I want to see when I want to see it.
Edit: It's also worth noting that participation in the programs is free both for the provider and end user.
As an example, the developer document solely for obtaining shipment rates is 98 pages long.
I still think Shippo has a long way to go, but they're doing great work and are very responsive to new ideas.
Can a Cessna 172 get you to New York? Sure, if you have the time. It'll be a long and monotonous flight though.
Now, with all of that said, your point still stands. GA flying is a hobby and almost always more expensive than hopping on an airline.