It's like anything else today, if you are going to dabble, you are going to be dealing with the same issues that a full blown business deals with.
Thing is, if you sell 100 items on Ebay that are all legit, you probably won't have a single return. The rate is pretty low under normal circumstances. But it happens, and if it happens to someone who doesn't do thousands of transactions on ebay, then it can look like it is some kind of ridiculous situation that "someone" should fix. When you end up with that perception, there are a couple choices of what to do about it. You can complain about it, which won't really change a thing. You can stop selling your used stuff online, but that's just silly talk. Or you can find a different way to sell it... But where?
There's always craigslist, but then there are a full set of DIFFERENT problems there. No guarantees as a seller or buyer, sketchy transactions, and annoying emails from window shoppers. Or you can find forums where potential customers hang out and post your stuff there. Again, downsides, like severely limiting your market, and you still have the same problems with sending stuff to someone you don't know. Or you can open your own store front and then you gotta pay rent, pay taxes, have a license, etc, and people will still bring stuff back.
If there was a perfect way to sell stuff and never have risk of any kind, someone would have discovered it and everyone would be using it. There isn't though, so you gotta work with what you have.
Personally, I already shared my story of fighting a $2500 charge back and winning. I know you can fight it and win. I have sold stuff that people want to return, even though I put "no refunds, all sales final" on the listing. And when it came down to it, I took care of the customer simply because I wanted to keep my reputation perfect in case I sell something else down the road. I've been burned dozens of times by the shipping company, but I still use them because what else am I going to do? I just accept that there is risk and use the best solution to sell my stuff.