"Some restaurants have tried this out, and it's backfired. "
Where I live, many restaurants have the "required 18% gratuity" thing and ask that you not tip beyond that. Maybe this is a PNW hippie specific thing, but a movement against tipping exists and is being ran by some good, successful, restaurants.
Making the tip required isn't a movement against tipping, it reenforces the idea.
Try increasing the posted food prices by 18%, or add a "18% owner boat fund", instead and see what happens. You won't last the week before you are bankrupt. The amount is exactly the same, so from a financial point of view there is absolutely no difference, but the experience of "helping out the little guy" is lost, and that will chase clientele away. For all the huffing and puffing we hear, actions speak louder than words. The reality is that customers like tipping!