Tipping is a staple of the hospitality industry and other parts of the economy, generating $40 billion in annual income for people who can really use the money. Yet tipping has become tedious. Passe. Abusive, even. With pressure mounting to raise the minimum wage and improve the plight of low-income workers, some crusaders want to ban tipping and raise prices so that people who depend on tips can earn more predictable incomes instead.