But menu prices have been increasing, at least matching inflation (from my experience, eating out seems to have even outpaced inflation in other areas).

A place that 5 years ago was $20 for a couple of people to eat was $40 when I went recently, ignoring tip. So a 15% tip went from $3.00 to $6.00, but the register suggested that we should be tipping 20%, $8.00. Also, they no longer let you order at the table, you order at the counter. They no longer bring the food out, they call out your number to come get your stuff. They no longer came out to provide refills, you had to go and ask for them yourself. About the only thing they did 'above and beyond' was bus the table after you left. I wouldn't have even minded all the 'self-service', but it was maddening when combined with a suggested tip that was way higher than when it wasn't self-service.

Not to mention similar tip suggestions for take out, where you take the mess home with you.

Yes but a restaurant bill has risen more or less EXACTLY at the cost of inflation so if 15%of the bill was okay in the previous decades, it should be okay now.

In fact this system makes hospitality workers among the few that have (the tip part) of their income adjusted to inflation. Everyone else salaried except for CEOs probably only got a 1-4% increase the past few years, not enough to keep up with the increase in cost of blrent, groceries and, well restaurant bills.