Earlier quoted context omitted.
I think you're looking at this from the wrong direction. Instead of starting from "what is my ideal experience, and why are people failing to deliver that to me," try thinking "what does the existing equilibrium have to teach me about this situation?" If you stop and think, you'll realize that the ubiquity of this "problem" for you is proof that your intuition is wrong, that you are an outlier, that the vast majority…
That's not proof at all. Stereotypes and confirmation bias are well documented phenomena. It's very easy for people to take a few examples of behaviors by people from a certain group and apply that behavior to the entire group when they aren't members of that group--despite what the actual statistics show. An example that happens all of the time in food service is assigning racial heuristics to tipping. A waitress ha…
When you are waiting tables all day, you're optimizing for two things: tips, and, even more so, limiting annoying situations. A hypothetical server who carries the bias you describe will learn quickly, like, within a night or two, that haranguing their customers about spiciness will result in both worse tips and a lot of extra hassles. In your example, you were so agitated about the spiciness that you even got their boss involved—that's a huge hassle for a server, a big waste of time and something that probably annoys their boss.
I can say from experience that servers do not have the luxury of making decisions based on arbitrary cultural factors. The data is being drilled into them all day, every day, and in all but the most unusual cases, servers will take the path of least resistance to quick turnover and tips. And if you want to deal in stereotypes, don't underestimate the practicality of immigrants.