Dear Ebay:

GSP should be a customers choice. If the buyer doesn't want to comply with Pitney and Bowel rules, then other shipping options should be available upon request. (,Opt-out) Buyers should have freedom of choice, and Ebay is depriving buyers from that.
The GSP is a good system as long as shipping could be combined, or smaller items that fits in a normal enveloppe and with low value can be shipped for low prices. Sometimes you do not need a $23,- courier to ship a $6,-, 80 gramm item that can be shipped through USPS for as little as $3,39.

By the way, please inform your USA sellers better about the consequence of ticking the GSP box. They have no idea what Ebay is charging. You use the fear of Americans to make a lot of money through a company that you own. ( Pitney and Bowel).
You are not complying with the freedom to choose a shipping agent.