Agreed. They shouldn't have to, but surely we can agree that if you're going out to have a nice time, made possible by someone who you know to be greviously exploited, that it would be cruel and unfair to deny them their only real source of income? Under those conditions, surely going to a restaurant at all is immoral unless you exchange the worker's labor appropriately, whether or not this obligation should befall you in an ideal world? Surely we can agree that in that moment, you are the one who decides if that worker will receive the income they need for food, clothing, healthcare, and housing, and if you will not provide it in return for your evening of leisure, it would have been better if you had stayed home and allowed that table to be occupied by someone who would choose to fairly compensate that worker?