I'm sick of packing lunches but have been doing so for most of my work life. In some cases, there just wasn't anything within a reasonable distance to where I was working and the place either had no food options on site or it was just inedible without getting sick. Boy, I could tell you some school cafeteria horror stories that would make the nastiest food truck seem like a gourmet treat!
Have also worked in a lot places that don't have a refrigerator which limits what you can safely store until lunchtime. Then there were the schools that had refrigerators but it wasn't worth using because the parents would always steal the teachers lunches.
Now I'm lucky enough to just go home for lunch except the time is so short that all I do is eat something very quick. I'm a slow eater so sticking around wouldn't give me anymore real eating time. Deal with that by snacking at work when I get a chance.
It's nice to take a diversion once in awhile but it seems those trucks tend to only venture into areas that already have plenty of restaurant and carry out options. I've never seen or heard of any around here and have a feeling that the town wouldn't allow them so they don't compete with the many restaurants. I don't know though. Either way, I doubt that I'd bother with buying from one.