Why some online payment service providers (like paypal) always protect the buyer?

[yataka]

I think it's real not fair to protect the buyer more, so some fraud activities alwaya happen. For example, the customization shopping on-line service is hard to be protected if someone want to have something customized on-line and then they asked to charge back the payment when they received the item with the reason of 'total different' which is hard to judge who's right because everyone has its own feelings on the custom item. Under this condition, the on-line payment service provider always protect the buyer by sending the money back. Actually i think it's not fair.