I'm convinced that those systems have deliberately be made to push the customer to tip (more) and therefore increase the transaction fee for the payment operator (Square most of the time).
Most of the workdays, I go eat lunch at "order at the counter" places. The Square ipad is directly visible to everyone behind me in the line as they can all see that I put "No tip". More than once, I have seen people look back to check if other people in the line would see their choice, and subsequently change it to a "socially acceptable" tip of 15%.
I never tip at an order-at-the-counter restaurant. If I place my order at the counter, and get my own drink, find my own table, etc., I'm not sure what there is to tip for.
Most of the workdays, I go eat lunch at "order at the counter" places. The Square ipad is directly visible to everyone behind me in the line as they can all see that I put "No tip". More than once, I have seen people look back to check if other people in the line would see their choice, and subsequently change it to a "socially acceptable" tip of 15%.