i think every country/culture has their own kind of restaurants that is the most common, casual, very affordable type of place that everyone can and do go to eat everyday.
basically think of where the lower class people go to lunch when they are at work and you will have the answer.
Most Helpful Girl
fast food joints
Most Helpful Guy
A question of price.
The 'mitraillette' is popular with HS students: https://en.wikipedia.org/wiki/Mitraillette
A cheap eatery is the sandwich bar (like the US Subway)
Another cheap one will be the chips seller (chips/french fries with fake mayonnaise sauce or ketchup):
Those who can spend a bit more will go to a McDo
Then there are Turkish and Lebanese falafel/durum sellers.
Pizzas can be more expensive0