When comparing an normal Italian restaurant to a Pizza Hut restaurant: The Pizza hut, will have specialized mostly on Pizzas, so like typical fast food restaurant they have a very limited menu card. While a normal italian restaurant will offer you whole menus including italian soups, italian main meal and side meal salads, a broad variation of noodle, gnocchi and cretin specialties, as well as typical italian seafood and lamb dishes. As well that I only have been few times in Pizza hut, but I think they wont have stuff like a winecard or waiters being able to recommend you wines for your menu. Just as from an real restaurant, I expect them to care for propper ingredients, so real prosciutto, mozarella, parmesan, while typical fast food restaurant simply will offer the minimum standard, but nothing more. As well that a fast food restaurant wont have any additional dishes in the menu, that need much time for preparation, like lambrips or other stuff. Or freshmade house Tiramisu and so on.
So in a restaurant a waiting time for your main meal of 25 minutes is ok, while if I go into Pizza Fast food restaurant, that offer me a limited menu to focus in serving me faster then a restaurant, and order a Pizza and needed to wait 25 minutes, I´d think they are a bit nuts. So fast food is not linked to me to getting it immediately myself at a counter, but simply everything that is fast done within about 10 minutes. Typical "sausage-hutts" around here offer you as well service, and unlike an McDonalds dont have everything prepared, but its simply stuff that is done very fast. So you order, the moment you have ordered they already throw the sausage in the bowling water, throw the Fries into the Fritteuse, and you are supposed to receive it at least in about 5 minutes.
Its simply about food, that is prepared easily without much effort and normally does not need longer then 10 minutes until being served. Pizza fulfills that. ^^