Reason not to use PostalAnnex - they grossly overcharge

I had a package that needed to go from California to Illinois. Being frugal, I wanted to pay as little as possible and yet get the insurance and signature confirmation for the shipment.  So as an experiment I've stopped by USPS, UPS, FedEx and PostalAnnex.
Everyone's rates for these services vary slightly, and I expected all of them to be very close. Indeed all of them were except for one. USPS wanted $39, UPS $42, FedEx $37 while PostalAnnex gave me the quote for their cheapest shipping method (FedEx) at $54! At $20 extra for each package (they actually get discount form the shippers due to volume, which accounts for the $3) , it's no wonder that PostalAnnex is a profitable business when all they need to do is put a label and have shipping company pick it up. But it does make me wonder - who in their right mind would ever use PostalAnnex to ship anything? $20 difference will easily cover the gas which one may use going to closest UPS or FedEx.
You may have different view on the topic, but to me $20 in a price of a shipping service determines the location I will go to.