It is a fancier version of craigslist, not a dumb down version of Amazon. Most of the time I only buy from seller with lots of good review and have things at stake, so I trust that if something goes south I can ask them to fix it. No way would I buy something $2000 from a homeless guy in the shelter sight unseen.
Sometimes you just have to do your own investigation before the transaction. Once I was selling the right to a new iPhone to be picked up from Apple Store internationally (so if things are not delivered I would not be able to do much when charge back happens). The buyer bid on it, using a commercial address of a business in England. I found the address and I call, there is no such person. I message to see if I can get her to pick up from their local apple store 3 blocks away from her address, no reply.
I bet she was surprised that I could get her to pick it up in person from the store so she cannot just lost the package. I end up having to ask ebay to cancel the transaction as a scam. Ended up selling it to a coworker instead.
Meg Whitman could have made eBay and Paypal the Amazon we have today, but instead she milked it to a craigslist. I'm glad she is not our governor and we know better (same for Carla Fiorina, who drove HP from a tech giant into a laughing stock as well).