This is a good point. I guess if people only trade cryptos it would be easy as ModulTrade would work as smart contract based escrow but if there are real goods involved it gets more difficult to prevent scams.
It is not impossible. Escrow.com offers such protection for online purchases, especially when using PayPal. Alibaba also has an escrow service but it seems to be full of loopholes.
yea indeed its difficult to remove all risks, unless the platform offers payback guarantee, which also may lead to some kind of abuse.
But we need to see the good in people, because most of us, are not looking to scam others.