If you can't afford to tip fully for good service, you shouldn't be eating at a restaurant. Order fast food, takeout, or make your own food.
Again, you aren't being realistic.
Going somewhere to eat is fun and entertainment. A busy family of four may want to go out to eat sometime to escape and not have to cook and clean up after a busy day.
What's crazy is implying that they can't afford to eat at a restaurant because they tip 15% instead of 20%.
Would you be OK with someone skipping out on the bill if they can't afford to pay for the whole meal? Is it not realistic to force a family to pay for the entire meal if they want to escape and not have to cook and clean up after a busy day?
You do realize your 20% minimum tip level for satisfactory service is higher than the average persons? (or the other waiters/waitresses that have posted in this thread must consistently give less than satisfactory service)
First, I think it might be helpful to clear up what I mean by satisfactory service. Essentially, I mean "nothing to complain about." If there were things you disliked, then it's perfectly reasonable to give less.
Second, as I said before, most people lack knowledge of the reality of the restaurant industry. Plenty of people think 15% is the norm because they believe servers make minimum wage. They don't realize that servers get paid 2.23 an hour. They don't realize that many aren't allowed to start getting that wage until they get their first table (so, if there is nobody eating, they sit around not getting paid). They don't realize that if a server is about to work more than 40 hours in a week, their hours are "rolled back" so they essentially only get paid through tips. Therefore, while 20% should be the norm, no one, including me, expects everyone to be aware of this, so the actual amount given is quite often less. Judging from my experience, the server range is from 15% average to about 22%.