$2.25/hr for 8 hours is $18. I don't know about the SF prices but in Manhattan you can get a "hot desk" for $30/day at some fairly nice places. I'd guess in Brooklyn you can probably find/negotiate something comparable to $18/hr.
Hey, that's roughly what a coworking office space costs! Except sitting in a parking spot, you don't get free wifi, coffee / tea, bathrooms, networking events, shelter from the elements, facilities security / maintenance...
So: I'm not sure how coworking fits into the larger point they're trying to make. Yes, residential rent is insane in San Francisco - no argument there. Yes, parking spaces that sit unused throughout most of the day are an unfortunate legacy of car-centric urban design. Both of these are solid and reasonable points to make.
But $400 / month for an office space that comes with a slew of amenities? That seems entirely reasonable to me, and definitely in keeping with permanent desk costs in other, less extravagantly priced cities.
I know from experience that I can't, and that's one reason why things like WeWork would not be something that I'd consider. I wouldn't even take a position with a company that uses an open office plan.
But there are apparently a large enough number of people who find that sort of thing tolerable that a business catering to them appears viable.