For those saying 'restaurants should just increase their prices', do you think the staff doing the ground work would see any of that? Increased profits go to the business.
Well, then we're getting into a whole different discussion about business models and exploitative workplaces: are we really saying that ALL restaurant owners/managers cannot be trusted to pay their staff to the extent that the staff have to collect money directly themselves if they're to make any kind of living? Is the restaurant trade as a whole basically crooked/borderline legal? I can't believe that it is - and it's quite a slur to imply that. In amongst the dishonest business owners, there are a huge number of fair and honest ones.
If we had good reason to believe that the trade as a whole were exploitative, then it would be our basic moral duty to boycott them entirely - like with questionable nail bars and hand car washes - not to condone their shady practices and turn a blind eye.
Changing the culture so that restaurants increase their prices and then pay their staff more on the understanding that tips are 'not a thing' at their restaurant would actually put more power into the hands of staff, as they would be told what their take-home pay would be, enabling them to actually have the knowledge they need to decide which one to apply to and which one to eschew. Restaurant A pays one wage, Restaurant B pays another and Restaurant C pays yet another. If all three of them increase their prices and two increase servers' wages whilst the other doesn't, guess which one will struggle to get any staff. Lidl & Aldi openly advertise their hourly rates when seeking new employees - which are presumably better than other supermarkets pay. Can you imagine if they said "we pay the same as the others, but you're allowed to ask for tips so that you end up with more"?
Like any job, it's up to the potential employee to take the best-paid job that they can get in their chosen field - so a restaurant paying below the 'going' or best rate would struggle to get staff and thus struggle to keep going, just like a business offering a salary of £30,000 for a CEO would have to function without a CEO and likely go under.
I've said it before on similar threads, but if charging an artificially lower price and then relying on tips from customers/clients to top it up really did work in the best interests of workers, then you'd have solicitors, chief executives and all other white-collar professionals charging significantly less and then asking for tips and/or adding 'optional' service charges.