I wonder if a part of the attraction isn't de-commercializing the experience for the diners? Paying up front, presumably via credit cards, means that the service experience is Uber-smooth. You never have to ask for the check, fumble with cards, or do the who-has-this-one dance with other people at the table. You simply show up, get treated like royalty, and leave when you're ready to.
I feel professionally obligated to quibble at one point:
Most reservation and ticketing systems charge by the number of customer transactions, the number of restaurant admin users, for equipment, or a combination of all three. The more business a restaurant does, the more they end up paying. As a business owner I hate such models. Adding an incremental user on my end costs a software company nothing – especially one that has a cloud based system.
You may discover, in running a software company, that it is really valuable to have the prices which you can charge scale with the success of your users. It's how software companies can bid down their lower-end entry points, since we can't conveniently sell our users alcohol at 80% margins.