Why don’t restaurants ban tipping?

Hear me out for a minute. Most servers are getting paid 20% tips. So in reality, they’re taking 1/5 of the gross revenue of the restaurant. Like others have said many times, servers are a basic low skill job. Why don’t restaurants just raise their menu prices, pay their servers a modest salary, clearly write No Tipping necessary on the menu, and pocket the difference? I don’t understand why any business would let their low skilled workers earn such a high percent of their revenue.