These small shacks I think are able to do it because they have next to no overhead. It's just some folding tables and a few chairs and all the prep is done somewhere else. The sidewalk area where they operate isn't even legal and once the police decide that they are going to take the land back they are out of business.

Almost none of these roadside things, no matter what they are selling, manage to stay open long term. There are a few standouts that end up getting a building later because they are so outstanding but these waffles wont' be one of them since this is a very common things that anyone with a waffle iron can easily replicate.