The "cultural difference" in Australia is that servers, etc. are actually paid the same (fairly high by U.S. standards) minimum wage or above for experience bar

The "cultural difference" in Australia is that servers, etc. are actually paid the same (fairly high by U.S. standards) minimum wage or above for experience bartenders. So tipping just seems kind of dumb in most cases. The bill is the bill and you pay it and move on with your night. I think there are many reasons why it persists in the U.S. On the server end, it makes it easier for a casual employee to make a reasonable amount for a couple of nights work and you would make much less if you were straight hourly. It also allows service industry employers to "staff up" on those busy nights and not have to worry about keeping too many on the rest of the week. While customers get to do some social signalling, I think that's mostly adjacent to the server and owner's pay scheme. If the U.S. moved away from tipping, they would need to pay a higher minimum wage, keep fewer casual employees that only work 2-3 nights a week, and the regulars would be either full-time or half-time which means the busy nights would have fewer servers, though maybe more experienced so nearly as productive for the ones that work it as a full time job.