Kogi is licensed by the State, so they have to have a sink and the ability for employees to wash their hands, as well as some other things. They also are required to situate within 200 feet of a restroom, which is why they’re always outside a business that allows them to use their facilities.
But your concern is on the mark, because there are many unlicensed MFPUs (mobile food preparation units) in LA.
Here’s a picture. The prices will be higher, but that’s to be expected.