I liked the article in general, but this got me: I usually eat at the same few restaurants all the time. They’re maybe 10% more expensive, usually locally own

I liked the article in general, but this got me: I usually eat at the same few restaurants all the time. They’re maybe 10% more expensive, usually locally owned, and the food doesn’t come out of a frozen pre-made bag before being tossed in the oven. I never tip less than 20%, and I’m not an asshole….at restaurants. I don't understand this thought process. Why not pay 100% tip then? Is the 20% number somehow magical and affords the ability to be elitist? So if I tip 15%, which is the average suggested tip in Western Canada, I'm somehow an asshole???