For one, imitation is the greatest form of flattery. A few succeed so everyone is trying it.
Also the younger generation is open to trying new foods, new experiences. trying out new things in life.
Also, there is a lot of cash crossing those food truck counters. Cash that is easily not reported to the IRS and taxed. Restaurants have rules and must keep records, pay taxes, have massive expenses for equipment, tableware, rent... They are in the hole even before they light the burners in the kitchen.
We have recently lost a Burger King and and a Friday’s...................