A tale of two purchases
More than ten years ago I purchased a Fine Scale Miniature kit (model railroading) for about $120. This was before paypal, before money back guarantee, heck you could still communicate directly with other bidders. I sent in my postal money order to a PO Box in Massachusetts and never heard from the seller again. He had pulled the same fraud on two other buyers that week and we were all out our money. No item, no refund, no recourse.
About two years ago I bid on a mint $2.60 Graf Zeppelin from a seller in Spain

Now Don would have done a search on this image and realized the pictured stamp did not actually belong to the seller, but I didn't.
After winning the auction and paying for stamp with Paypal, I received this stamp in the mail

Needless to say I was a bit (understatement) disappointed and replied to the seller that I would be returning the stamp for a refund. Which I did using USPS with tracking. Well tracking to Spain is not that great and is not accessible over the web. I would try and communicate with the seller to ask if he had received the item, but he had gone dark.
I opened a case with
ebay, but by now I was beginning to run up against their 45(?) day window for complaints and I still couldn't prove that the seller had received the stamp. The USPS requires a 30 day wait before they would look into the issue. Finally 30 days was up, the USPS started to request documentation from their Spanish counterpart. The
ebay window was about to close and I called them and implored them to extend the window, but they refused. The window closed and shortly thereafter I received the proof that the item had in fact been delivered. Good for me, but too late for
ebay.
But not to be deterred I sent all of the information to Paypal. They agreed with my case and within a week I had the money returned to my account. I don't know if they were able to claw back the money from the sellers account (optimal case), or whether they found themselves on the hook. If paypal had failed I would then have appealed to my credit card company, which also has a money back guarantee.
So here in 2019 there are many levels of protection and while
ebay didn't come through, their subsidiary Paypal did