The guy in the article wasn't completely moneyless, he just came up against the recurring costs of taxes/rent which can trip up the unorganized.
Google car expense is overplayed. In mass production and with competition the cost would go way down.
Also, if the government makes the 'homeless' drive to specific places out in the desert or something, that's better than the current situation where you're exposed to other homeless and dangerous people.
I actually wouldn't mind going 'homeless' for a while to save money on rent, but currently it's really dangerous to do so. Moving to low rent places is also usually more 'dangerous', especially with children. With a driverless car you can just take your family out into the desert or forest and pretend you're camping.
The current system of full-time rv-ing is quite hard because of parking restrictions and because sending kids off too school and getting groceries from out of town is hard, and because the rv's are too small. With self-driving rv's you can have a few of them to space out in.