Only some big, well-known restaurants are an exception because people already known them and know to look for them. They are big enough to have online shop for food delivery and some form of delivery system.

For other places, it is not like that. They need to be visible on platforms that people use. If they are not there, people don't order take-away food because they mainly use applications which provide decent-enough catalog about available restaurants with delivery option and easy payment process.

Typical platform monopoly problem exists because people tend to be lazy and it is hard to get visibility on traditional search engines, when they are flooded by ads for the normal users, and then if you filter them out, SSO spam, which might not be related to restaurants, and then finally, competition against other restaurants.