It's not just a case of increasing food prices by 10% as 100% of the service goes into wages there are no costs, you'd need to increase food prices by much more than that to make the same amount of profit to meet the staff salaries.
So how do supermarkets manage to give a simple price for what they are selling and neither expect nor actually accept tips? They need thousands of staff to make their business work, but they factor this into the prices they charge the consumers - there's no extra tip for the delivery drivers, shelf stackers, checkout assistants, HR and payroll managers etc. Whether they pay a fair wage is debatable, but if not, it is their sums that are wrong and not the principle.
What's the point of running a business if you expect your customers to run part of it for you, instead of just being allowed to be end consumers paying a stated price?
How can somebody be capable of factoring in all of their other costs such as building purchase/rental/lease, business rates, taxes, accountants, utilities, kitchen staff wages, their own profits/livelihood, appliances, furniture, crockery, cost of buying in the ingredients, provision of toilets, cleaners etc.... but they somehow still need help to be able to work out that one element of how they can include their staff costs in the overall budget? Either they're not very competent businesspeople or otherwise their intent is to deceive and confuse for their own benefit.
I'm absolutely not asking for lower wages for serving staff - I just want them to be able to rely on actual guaranteed wages, ultimately funded by non-schemed customers who are given an honest all-inclusive price to pay.