Ask HN: [Naive What-If] No-Fee Version of Food Ordering App

I don't have any entrepreneurial experience, hence “naive”: let's say I wanted to help small restaurants by building a Grubhub-like service that allows people to order food without taking fees myself.

Preconditions: - I can build front-/backend- support myself. - I don't want to make or lose money on this. - Credit card fees (if necessary) will be passed onto the restaurants. - Restaurants can enter/change menus themselves. - Customers can order through the service (online) or phone (resto)

What am I missing? Would this be unrealistic (or not)?