First off, I've never heard of anyone being able to call any bike manufacturer direct and get parts. You always have to go through a dealership (or a distributor when you're buying parts over the internet)
I don't like having to go through my dealer for parts, and I'm absolutely certain none of their wrench monkeys would have the slightest idea what to do if my Zero had problems.
The fact remains however, that the dealers really marketed the Brammo and Zero to me by giving me test rides. I was completely uninterested in EVs before I got a "we're doing no-commitment electric bike test rides" email and went because I was bored. I'd sorta vaguely heard of Brammo and I had NO clue who Zero were.
This is completely unlike Tesla. Everyone and their dog knows what a Tesla is, and wants one. Tesla doesn't have to market themselves. As a matter of fact, they get free publicity from pissing dealerships off.
But once you buy the bike, you don't have to get parts from *that* dealer.
Zero doesn't have distributors yet, and I don't yet know any Zero dealers that sell online. I had a Suzuki SV-650 with a Suzuki dealership a mile away, yet I ordered parts from Ron Ayers, a big dealership in North Carolina because I could go to their site, check their parts microfiche and go clickty-click sold. (I'm in Florida, BTW) I'm also lucky because I do all my work, down to splitting the engine cases and replacing transmission gears, so I don't need a dealer service department.
The only big Zero dealer I've heard of is Hollywood Electric. Would they do drop shipping like Ron Ayers? I'm actually thinking of buying an Elcon 2500W charger from them eventually. If they won't sell it to me, there sure as hell isn't anyone local.