Just distribution of numbers. Even if 50% of the customers that go to a restaurant don't tip, it doesn't mean that the server will be fired. Because that 50% should be spread among all the servers of the restaurant.
The bullshit with tips is that it's based on the cost of the food. How about tipping based on the level of service and how long you received attention?
Consider these scenarios: I get a $8 meal at packed Steak 'n Shake, but I receive excellent service and spend and an hour there with my friends... Vs. I goto to a steak house to treat myself to a very quick, nice $40 lunch break and spend only 30 minutes there.
Does my Steak n' Shake server really deserve only $1 an hour from me? Does my steak house server deserve basically 8-12x that an hour from me?
Does a server who is dividing her attention 6-ways to service multiple tables deserve more or less than someone who has the ability to focus one 1-2 tables?
I can imagine a restaurant that lets you check-in for seating and allows you to place orders on a touch screen. Where the fountain drinks are setup like a fast food restaurant. Where an order-up comes to the counter and you get it yourself.
I can imagine a restaurant having that available, alongside a bidding/review system. Servers can check-in when they're available and lazy customers can place a bid if they want a server. Servers can accept the bid for service, and they can compete with each other for them. Diners can review servers, servers can review diners (or confirm/deny payment). Busy servers have less chance of seeing and accepting new bids, just because they're busy.
Restaurants could be certified for the business model. Servers could be certified for the business model, and for the restaurant menu. Allowing servers to work freelance at any certified location.
Of course, now that people can serve themselves, and servers can low-bid each other, and the server is freelance instead of employed... You'd most likely see average wages and tips drop until the market balanced itself and less servers afforded to do the position. But then if a restaurant had demand for servers, they could also offer to pay a mini contract for specific servers to come in at certain hours.
It'd be an interesting and radical change to the food service industry. No clue why I'm mentioning this.