Surely the theives/fraudsters are the buyers who put the claim in against you?
Sure i dont particularly find paypal amazing, but it gets the job done, and as a buyer i've managed to get my money back from genuinely bad sales, and never been shafted as a seller.
Exactly the same thing happens with Streamline or any other real card transaction system. We've had customers use our services for months without any issue with us charging their debit cards, get in a hump about something and call the bank saying "I've never authorised these people to take money from my card". Streamline then immediately freeze the disputed amount (usually every penny we've taken from taht card, which can amount to thousands) and send us a letter asking us to prove we were entitled to take the money.
Caused us big problems (and big losses) becuase we're selling a service, not physical items, so theres no way to show items being shipped out. We've since amended our contracts to include the card mandate which people have to sign before service commences, but its still a hassle, and theres always the risk that streamline could dispute the authorisation given on the contract, and theres ****** all we can do about it.
I actually find it quite annoying when people use ebay, and say no paypal, given that accepting paypal is a requirement of using ebay. They are the same company, so you cant really sit there dissing paypal, then happily give your money to ebay.