I think that is part of the issue. Nobody really knows if you're supposed to tip at an artisanal grilled cheese food truck. If it was Chipotle you wouldn't tip. If it was a hot dog cart you wouldn't tip, but you also wouldn't ever order $170 worth of hot dogs. Do people tip for big orders at Shake Shack? If not, I'd say you don't tip at fancy food trucks, either.

It gets trickier here in the future because if the business is using Square and you pay with a card there's always a tip solicitation screen before the signature screen. This has caused the unintended effect of me always paying for my third wave coffee in cash.