Because by not including the price of labor in the price tag, the company allows customers who are more willing to buy a product if they can stuff the worker more access to the goods and services they're selling.

This let's the collude with bad or non-tippers to stiff the worker.

We absolutely must not give a pass to shitty people who are "anti-tipping" but continue to shop at industries that run on tips.

EDIT: I actually want to be more explicit here, fuck you specifically if this is your attitude frazorth, and fuck anyone who agrees with you. The "Americans" deciding to let you steal from their employees by letting you pay them or not, instead of requiring you to pay that extra money and then passing it on to the employee are absolutely at fault, but if you fly over here and expect not to tip the desperate workers who are waiting on you hand and foot in restaurants, hotels, and on delivery apps, I hope you choke on your food and fail to make it back to nonce Island.