@kinetix No, there's no question about it. If you can afford a dinner at a nice restaurant, you can afford to make a server's night. There's nothing material preventing you to do it, it's only a matter of personal choice. If you have enough income to pay $100+ at a restaurant, you absolutely can drop an additional $20 for the tip on top of the expected 18-20%.

I personally don't always do it despite 100% being able to, so the original post is a nice reminder in that regard. When my financial situation was more precarious, I simply didn't get dinner at nice restaurants which ruled out leaning more on the tip.