I reckon everybody needs their 15 minutes.
Picture this. You pay the bill. The guy says if you don't pay the tip I'm calling the cops. And then you wait around for the cops to show up. Gimme a break! I'd have been long out the door.
What I really loved is the manager claiming that they'd offered to comp the food. Uh, huh! Let's see; we'll forgive call it fifty bucks in food, but then have you arrested over $16. I don't think so.
French Fries: More than an aberation, there's a possibility that they're illegal. Most of the time the "notice" is buried somewhere on the menu where you're not likely to see it. And it's not something you agreed to in the first place. So all you have to do is claim you never saw it, and, most likely, won't be liable in the first place.
Many a parking lot has learned that lesson, for instance, when they found the judge ruling against them for car damage, despite the disclaimer printed on the back of the ticket stub.
That aside, I've always despised the concept because it's one of the things that have encouraged the high levels of bad service we've all been subjected to. After all, if I'm going to get the same time whether I provide good service or mediocre, what's the point of working hard?
When I was serving (we called it waiting tables, in those days) I used to love large groups. Going that extra step with them usually resulted in a tip that was larger by far than you'd have gotten with the same number of people spread out over two or four tops. I didn't need an extra help from a required gratuity.