Would that service be indemnifying the seller from fraud? Or is your assumption that the platform would just make the right call?
Probably it's because the platforms don't want to make services to root out fraud because then they become more responsible for owning it. Outside services can't break in because the platforms aren't going to put trust in them. Those services would have to own the cost of fraud.
Probably it's because the platforms don't want to make services to root out fraud because then they become more responsible for owning it. Outside services can't break in because the platforms aren't going to put trust in them. Those services would have to own the cost of fraud.