I spent about a year in 2003 trying to launch a similar start-up. Restaurant owners told me that they would gladly trade a normal distribution of customer satisfaction for consistent-but-average experiences. Why? If you have a great experience, you might tell a few people. However, when you have an awful experience, you'll tell a hundred.
Those owners probably aren't great at training their staff and/or don't understand the intangibles that make for a good service experience. You might be able to sell the owners on your product. That doesn't mean the owners can sell their customers on your product.
The owners understood quite well what made for an amazing experience, but they didn't feel they could ensure that each customer would receive that experience given the issues they had in hiring and retention. One thing that shocked me was that I didn't get pushback on the likely increase in credit card usage. While 1.6% is a horrible portion of net margins, it's a small price to pay for keeping greenbacks out of employees' hands. There's a shortage of competent people in America who are willing to serve food at [Chain X] for more than a few months while finishing up school, etc. Most who will opt into serving long-term will seek higher-end restaurants.