1. Not tipping in the aforementioned scenario is so far away from qualifying as "fucking with" anyone
2. Not only would spitting in food get you fired but it's also a crime. Do you really think it's common for people to be this reckless with their livelihood?
It's a restaurant. If high flying executives with great careers can commit crimes to make a extra buck, the person flipping your burger isn't going to be much more pragmatic.
Jesus, fuck this—it's all too complicated. I'll just cook at home, thanks. Costs less, way healthier, tastes better and guaranteed to contain no bodily fluids. The enshittification of the food service industry is complete.
This is what I've done. There are a few restaurants that I've come across that have mandatory tipping, and I'll never go back. I don't think it's insensitive to believe that it is not the customers responsibility to pay for the employees.
Raise the prices, get rid of tipping, it will make everyone happier.
This is the way. I recently got an oil change, and at the end I was prompted to tip with the default 20%. I changed it to zero - the person doing the work is certainly being paid market rates and well above minimum wage (even now, why do I feel the need to explain myself?!) and I’ll never go back to this chain.
The guys likely to spit in the food are the same people who don't care the slightest bit about the business and are probably going to end up fired after a couple of months for not showing up getting in a fight with a coworker or manager. And this isn't me trying to bad mouth service industry folks, it's just that people who are working in fast food are usually are not in that situation because they're making life decisions that lead to financial success (again generally not specifically). The point being the person spitting in your food isn't going to care if you come back.
I worked in food service, mostly FOH as a bartender/server, and at no point was I angry enough at a customer to spit in their food, pee in their drink, etc. It just wasn't worth the risk or effort.
The most we would do is serve you slower if you're being a jerk.
I can't speak for every food service worker, but most FOH are too busy/indifferent to really care.