Whenever I dine at such a place, I give a 100% tip because it’s easier math and it incentivizes me not to patronize such businesses. (I only go with friends and I never make the suggestion.) Just saying that because I disagree with this perspective; do go to these restaurants and don’t tip if that is your choice.
Tipping used to be a gratuity. It’s a way to say, “Your effort was exceptional and I want to show you how grateful I am for it.” Tips are no longer exceptions, nor gratuitous: they have become an obligation, as you say. I reject this; I am not responsible for the wage of someone I did not hire. I’m not even responsible for the success of the business, except that I owe them what I agreed to pay when I ordered. It’s like every restaurant prices their menu incorrectly and they expect their customers to correct them.
(There is a Prisoner’s Dilemma for the restaurants: if I start paying my staff well, I have to raise (advertised) prices but people still think tipping is necessary so they’ll see my increased prices in that context and be more likely to go to one of my competitors. I don’t mean to say restaurant owners have an easy out, just that the answer to patronize these businesses regularly, while also tipping generously, perpetuates the situation.)
Is it wrong for someone to order carryout from such a full-service restaurant and not tip? If so, what would they be tipping for? If not, how does the wait staff get paid from the order when they’re primarily paid with tips?