The total cost to customer (or taxpayer) shouldn't change much in theory, just the route by which the serving staff get paid.
The American assumption is that a withdrawable financial incentive is the best way to ensure good service. The European/Aussie approach is that they are being paid to do a job, so good (enough) service is a baseline expectation. I think a lot hinges around what the expectation of 'good service' actually is.
Americans want big smiles and chit chat, while Europeans want expertise. That's obviously a huge generalisation, and there are plenty of exceptions, but largely it illustrates the different expectations towards a dining experience. In North America, waitstaff are typically young and higher energy, and doing the job as either a stepping stone or as a side gig. In much of Europe, it's considered a decent job worthy of a career. You're expected to know about how to recommend a wine or explain a dish. In the same way you wouldn't tip any other professional (accountant? mechanic?), you don't tip waitstaff. But you also don't expect them to pretend to be thrilled to see you even if they're not, nor do you expect them to pretend to care about what your plans are for the rest of the day when they hand you the POS machine...
I know which one I prefer, but as the endless complaints from Americans (and Canadians, to be fair) about perceptions of poor service in Europe indicate, I'm not in the majority here...
