My guess would be that banks expect further price declines of more than 10% on properties such as the ones you’re looking at. Consider yourself lucky that you can’t buy one and rent a nice place for the time being.
Lots of people have 20% down. Remember that there are many buyers who have sold houses here in which they had a lot of equity. There are also people with access to family money and just plain rich folks too.
Not everyone gets to own an $800K house in Encinitas. Lucky for folks like us we can rent them for $2500/mo 😛