Every successful waiter knows what it's like to be under-appreciated.
That feeling of knowing that you'd do anything to please a total stranger is something that a career waiter can't just extract from his psyche like a skilled neurosurgeon. Many waiters find that they are able to make their living selling, but what is it that keeps a skilled waiter from making a respectable stipend as an actual salesman?
Salesmanship is a logical next step up from the base floor of "Occupational Order Taker." It seems that anyone who can establish him or herself as a waiter could have potential as a salesman, and what waiters do (if they enjoy being tipped) is make alluring recommendations to enhance their guests' experiences. If you suck at recommending dishes and beverages, you become an order taker. So in essence, what makes the occupations of seller and salesman different?
I've taken a long hiatus from regular restaurant work to actually DO sales, and I've since found it relatively unrewarding. The fact that family men, scholars, public servants, and circus folk can serve people and make a menial living and be treated similarly is both fantastic and comforting, but completely sucks balls. We all keep doing it however, because we find enough comfort in providing strangers dinner because it seems preferable to any other time-consuming, emotionally limiting professional endeavor.
That's why people with decent jobs still keep a couple shifts waiting tables on the weekends.
When a guest sits down at your table, he or she kind of understands that you are there because you HAVE to be, and that servitude isn't ever glamorous. When a person complains about a dish you didn't cook for them, they're generally innocuous about it because in essence it's not your fault.
I once knew a great lawyer who studied and worked hard to dominate her profession. She kept five shifts a week waiting tables because it was good money, and because it was comforting and equally tormenting. It ended up ruining her social life because the effort she put into selling was dominating her life as a good person in the legal profession. When an implacable ass-clown at one of her tables yelled at her on a busy night for messing up a slightly intricate order, she broke down in the back of the restaurant and swore she'd never come back. I remember asking her why she never cried in a courtroom for defending a family from the crazy heart-breaking rantings of a drunken father lying to save his shitty life, and to this day never got a comprehensive answer. Having left the waiting profession for good, she is doing much better.
Life sucks as a middleman. The true power of it is that you find a way to make your customer's experience worthwhile. When a customer complains, you tend to establish yourself as a professional when you empathize with them and work to fix their every trouble. Either that mentality drags you into a deep dark hole, or it lets you believe that eventually you will find redemption as a "good person."
Sales contains none of those ideologies. When you're selling a product, you're promoting value, gaining trust, and easing someone's mind. If you're falling short of any of these tasks, you're probably just a waiter.