Agree with everything you say. However, for large, heavy, bulky items, it's actually cheaper to come via GSP. Sometimes significantly cheaper (for me it was $US69 as opposed to $US 135).
It's easy to see at a glance which sellers are using it, both in the search results and the actual listing. I just avoid those sellers. If it's something that's really hard to get, I ask the seller if they would be willing to post via USPS. Quite often they are. Quite often they don't even know they are opted in to the GSP.
The thing I really hate about it is the inability to combine postage for more than 1 item. If each item has $25 postage and you buy 5, you are expected to pay $125 for something that would normall cost about $18 sent via USPS. So many buyers are being caught and actually paying it thinking if they don't, they will be reprimanded somehow. Thankfully, when I got hit with over $200US for postage, my seller offered to cancel and I gratefully accepted as soon as the requests came in.
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