Don’t understand the concept of 20%+ tipping culture

Ok so just background I was reading a post about a guy who left a 25 dollar tip for an hour service and 190ish dollar meal. The waiter returned the check and said he doesn’t accept less than 20%. So of course you can guess how the comments section went from there.

So my thought and question is how does the 20% rule even make sense. Let’s say he spent an hour on a 100 dollar meal and only tipped 20 bucks and now somehow it’s acceptable despite probably the same amount of work from the waiter? How does bringing a customer a 50 dollar steak instead of a 10 dollar burger justify a higher tip despite it being the exact same service and amount of work?

The whole percentage of the check determines the tip concept just makes zero sense to me.

And just to end I’m not an anti tipper. I just see these arguments about tipping and I wonder how the rule even got started or how it makes sense to people.