Part of it is because visa and mastercard charge these big fees for their service that make it difficult for small businesses to cover costs and be competitive. A few restaurants by me that are legit brick and mortars (versus stands), have card service, still offer a cash discount of 4%. For stuff like food trucks or table setups on the sidewalks, I don't blame them for going all cash and flying under the radar from the IRS, considering how difficult it is to establish a small business in this county and maintain everything in order as far as the local/state/federal government are concerned. Its almost like the laws are designed to make it difficult unless you have a 'fixer' on your side telling you what forms to file and how to deal with things from the government, just based on people I know who run businesses here and have had to use fixers themselves to understand the byzantine tax process or other licensing issues.