After 20 years, way back when Ebay could hardly go a day without shutting down, and most sellers were your pleasant amateur group, we went through many changes and problems, not the least of which is Ebay's greed, for their piece of the pie, and the tricks and crooked scams many sellers and buyers resort to.
I felt I had pretty much seen it all, and did my best to be careful who I bought from and who I sold to.
I still get buyers who insist they want cheap shipping with no tracking, then claim they did not get the goods, and sellers who never mail the merchandise, use a tracking number that goes nowhere, never used, and lie after lie about shipping problems, banking problems etc to the point after 2 months, nothing is resolved no matter all the promises I got from Ebay customer service and Paypal.
The biggest issue is the automated software which has glitches, claims inaccurate results, and you can't argue with a machine. Some sellers know how to trick the system on Ebay. I finally had to chargeback the amount on my credit card. The last resort. My advice: do use your credit cards as a buyer, and do use tracked shipping as a seller, no exceptions, The big corporations can fight it out, the ones that make most of the profits: Ebay, Paypal, Post Office and Bank Credit cards.