Why do restaurants and bars suggest that a tip be made against t

Sea Isle City - Why do restaurants and bars suggest that a tip be made against the tip of the bill? Twenty percent suggestion of a tip to the total bill may add $2 or more to the tip on the basis of tax collection, and not for service. If one gives that extra money as a tip, should that not go to the state or local agency for schools and services? As for the waiter, pay them a decent salary so they are not agents of the tax collector. Check receipts to see if they are using tax for waiter compensation.