Disclaimer--I work as a software dev for a real estate brokerage.

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.