buyer/seller integrity question

I don't want to come across as a hack or a scammer but I have to state the following:
I've sold cars on ebay and never aimed to get rich from it. I built a few A bodies and made a little money on each one. Most of the benefit that I got was the fun of the build. Some people really work the rules to take advantage of others with ebay sales. It seems like the buyers are given all of the rights with the sale.
One guy bought a Dart Sport and contacted me about a few small items that I legitimately missed so I sent him a box of parts to correct the mistake.
Another guy bought a car that went across the country to what turned out to be a used car lot. The buyer bitched up one side and down the other about things that were NOT an issue when I had the car. He didn't make any threats but according to ebay, he could have. I could have been on the hook to refund his money and pay for the shipping BOTH ways to get the car back. The car barely made the low reserve I had set so this would have been a real shitty deal if he pushed matters. The man knew what he could get away with and used it to his advantage. I ended up refunding some money and he never contacted me again. THAT was a shakedown that I had no choice but to go along with.
Ebay is ****. They don't care at all about the sellers. I've sold two cars after that debacle and was extremely clear about everything. One had a $5000 reserve but bid to $9000. Why is it that the highest bid didn't result in the buyer being the more picky one? No.....It had to be the assclown that barely made the lower reserve. It is the cheapskates that still think they deserved more.