I understand why some restaurants add a 15% tip to bills of fare for large groups, but that doesn’t mean I like it. 
  Individuals can hide in a group and can be cheap with the tip anonymously. The waiter’s disdain is spread over everyone rather than focused on the cheapskate. 
  An easy solution is to issue separate checks to individuals within the group. Experiments show that resulting tips are higher. 
  I am not one of those who argues that tipping should be abolished and service workers’ pay be increased to make up for the loss. When reward is the same for a doing a lousy job as for doing a good one, there is less incentive to do a good job, to be superior rather than merely adequate. 
  I first encountered mandatory tipping a decade ago in New York. I left the tip on the table in cash, took the bill to the cashier, and insisted he charge my card only with the pre-tip total, that I’d left the tip on the table. 
  It did not help that the cashier understood less English than the average foreign tourist. It took a prolonged huddle of cashier, waiter, and one or two others——translators perhaps——but I prevailed. I never ate there again. 
  This week, I had to scratch one of my favorite Puerto Rican restaurants off my list. Its computer now adds a precise 15% to the subtotal. 
  The waiter was apologetic when my companion and I told her we’d like to speak to the manager. 
  I explained to the manager and to our waiter that a mandatory tip is not a tip but a surcharge. It is an insult to the customer and to the waiter. It punishes superior waiters who might receive a higher tip and rewards lazy ones who do nothing to earn even the 15%. 
  The manager said the owner had instituted the new policy. 
  We asked him to tell the owner that at least two regular customers, who reward superior service with tips closer to 20%, are insulted by his new policy and will not be back until it is changed. 
  A couple of evenings later, I tried a small restaurant down the street from the one I’d abandoned. The food was excellent and the service, superb. A note on the menu warned that a 15% tip would be added to bills for groups of three or more. 
  It was the kind of place in which the owner wanders among the tables, greets customers, and makes small talk with those who seem open to it. 
  I mentioned that three was the smallest group size subject to a mandatory tip I’d ever noticed. That launched a discussion of tipping in general. 
  I’d read years ago that groups of women leave the smallest tips. The owner says that’s changed, that the growing number of professional women tip as well as men. She said the worst tippers are Canadians. 
  I suggested separate checks to keep the percentage up where it should be. 
  She said that tourists from many countries do not tip when they travel, singly or in groups, because they either come from places where tipping is not customary, or they are accustomed to having the tip included in the bill. 
  She said that some people don’t look closely at the tab and tip on top of the billed 15%. 
  I told the owner I though mandatory tipping reduced a waiter’s incentive. 
  Her staff is small enough that she doesn’t see that as a problem. Each worker knows what each of the others is doing. Their incentive is to make customers return frequently as much as it is to earn a good tip. 
  Another of her policies, and not an uncommon one, is to pool tips and include kitchen staff in the division. She wants the chef to have a stake in how well he does his job.  
  I told the owner that I often dine with my crew, and that means three. I requested that, should we all come in for dinner, that we not be billed for the tip. She seemed amenable to that. 
  If three of us do go in and they insist on adhering to policy, we’ll ask for separate tables and talk across the spaces between them.