>the system has a loophole: large swathes of the city are designated as roads, sidewalks, highways (which is a technical term for the road allowance). These areas of the city are completely free to use, for anyone, on the condition that it's a short-term, passing-through, sort of use.

You're making it sound as though food trucks stop in the middle of the road to sell their stuff. In fact they use designated parking where it would be completely legal to keep the vehicle for the same duration otherwise. Also, the business model of selling from a truck isn't going against some core concept of land ownership or something (witness ice cream trucks, which have operated with little friction for 80 years or so). The problem is with the "system" defending entrenched interests against innovation and using BS regulations (see the article) to do so.