If your job is just to drip coffee you shouldn´t be entitled to get more out of every hour, unless you give a great service to the customers and they decide to tip you. If customers are forced to tip you regardless of the service you give, and you are great but your coworkers does a shitty job, making tipping same for everyone removes your incentive to give a great service, hence making the service lower and the customers still have to tip regardless of it. Meanwhile the company does this to avoid paying workers more for each hour, so defending tipping is actually defending the company strategy to avoid raising salaries.