Why are tacos from food trucks better than tacos from restaurants? Felix Salmon has a theory:
My favorite theory is that it basically comes down to the amount of time that elapses between the taco being made and the taco being eaten. Fillings can stay warm and delicious for a while, but the tortilla really is at its very best within seconds of coming off the stove, rather than getting soggy at the bottom of a tortilla warmer brought to you by your server. I suspect that if you could walk into the kitchen of a decent taco restaurant and get the chef to make you one then and there, it too would taste better than the same taco ordered off the menu.
This sounds right. My favorite taco place (a restaurant, not a truck) seems to deliver tacos to my table in a pretty fresh state. I'm no foodie, but the shells seem to be hot off the griddle most of the time, and that does indeed make the taco taste better.
Alternatively, if we did a blind taste test maybe it would turn out that tacos from trucks aren't any better than tacos from restaurants. Perhaps we just like the idea of eating food from trucks?