Xpansive, in the USA, bar owners aren't going to pay a bartender or server $30 an hour because of payroll taxes alone. Very few people realize that a $30 an hour server on the books costs a restaurant owner roughly $90 an hour after all is said and done. This article doesn't take that into account. The article says that tipping doesn't provide better service to minorities. If you abolish tipping altogether, you'll end up getting McDonalds style employees working at your place. They aren't going to treat anyone well.
BBQS in lower Manhattan is frequented by African Americans mostly. For a long period of time, the servers would complain that the clientele just did not tip. They would run their servers around and bark at them, then leave a small (if any) tip.
BBQS now adds the tip to ALL orders after 8 PM.
Server morale went up and the business has not suffered.