system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do most fast food restaurants specialize in hamburgers and french fries? Why isn't there more variety?

If you're in the mood for a cheeseburger and fries, you're in luck because you have your pick of McDonald's, Burger King, Wendy's, Sonic, Carl's Jr., White Castle... the list goes on.

Hot dogs are a well-known and beloved American food too, but off the top of my head the only place I can think of to get a hot dog is Nathan's, and I've only seen a handful of those over the course of my lifetime.

Why is this? How come so many restaurants can serve the same type of food with all that competition?
gpt
Tons of places offer hot dogs: street vendors, Sonic, Dairy Queen, and many more regional places.  Many places offer Mexican food.  Many places offer deli sandwiches.  Quite a few Asian places could be called fast food, even if they are rarely drive through.  I'd say they have competition.