I read a great book a while ago called "The Middleman Economy" which talks about all the ways that middlemen provide value. Sounds like Seamless isn't providing much value (at least at the time of writing), and those take rates are pretty high for repeat orders.
At the same time, as a restaurant, why wouldn't you pay 20% if you were going to be out of business if you didn't (as one of the quotes in the article mentioned).
As an owner of a restaurant and beer garden - experiencing first hand their unreliable technology, driver dispatch, and support staff - I dropped them after a few months.
We also added notes in all our deliveries as a disclaimer that we did not hire the drivers - and that customers could call us directly for future orders - bypassing Seamless - to help support their beloved local business.
I wonder if a restaurant association could take on the cost of building a competitor that could compete with Seamless; Especially if restaurants manage to convince the public that Seamless is as toxic as Uber, a solution to absolve people's guilt that is just one click away might be successful.
I say this because I hate having to get on the phone.