its a big issue i have with bitcoin. no charge backs makes it easy for you to get scammed and the scammer gets away scott free.
its an issue i have with creditcards/paypal.. ALLOWING chargebacks.. a customer gets the goods and gets their money back, because its then easy to chargeback scam a seller to get goods and run off with the money aswell scott free
if you have proof of delivery then you wont have this issue . i always add tracking to my shipping so buyers cant say they didnt get the item.