Grubhub did raise $50M a couple years ago: http://techcrunch.com/2011/09/20/food-delivery-search-engine...

While not a direct indicator of success, I assume this means they are posting some encouraging numbers.

I think a lot of restaurants don't join these services, because it costs them money on each order, and they have to find a way to deliver the food, which is a distraction. For this reason, these services sometimes have the least common denominator in terms of the restaurants that are willing to deliver (i.e. restaurants that don't get enough real world traffic).

What evidence do you have that these services aren't popular, and how do you define popular?