That said, I've spent some time thinking about whether just changing the laws would have an impact. I think the issue is bigger than this.
I think that there are lots of marketplaces have sprung up via the internet, but as far as I know, the significant ones all offer products that have one of these characteristics:
* the consumer buys them often [for some definition of often] (airplane tickets) * the product is fungible (books, cars) * the product is relatively cheap (stuff sold on ebay, amazon)
All of these characteristics lower the risk of purchase. Housing has none of these characteristics. And I don't know how it could, short of a real manufacturing revolution or more houses built out of shipping containers.
Speculating, the agent knows the laws, but also pays some of her commission to an attorney who does the real work. The agent is a middle man.