And it seems to me that if you can’t afford to pay your employees a living wage then you can’t afford to be in business, let alone turn a profit.

If they can't afford to be in business, you can't order groceries. So maybe a bigger tip is how you continue to have access to a service you want.

The question is whether there are enough customers willing to support a decent wage for the people who do what the customers want done. Unless we subsidize wage earners via government action (a UBI), we must subsidize them by voluntary action (tips). Otherwise, the things they do won't get done as their employers fail for lack of customers.