Vancouver

Traditionally, tipping is unrelated to low wages. It has to do with the transactional structure related to serving alcohol. There is good reason why the practice emerged in bars and why many of the laws established around tipping refer specifically to alcohol.

Unlike other liabilities which are shouldered entirely by the business, the liability related to alcohol falls on the server. Likewise, the server has free rein to reject your request for alcohol, even against the wishes of the business. This is so because there is, legally speaking, a direct business relationship between the server and the customer when alcohol is involved. Tipping exists because of that business dealing that exists outside of the establishment's business dealings with you.

In the trades, when you do work directly for a customer – done so under your name with you bearing the responsibility and liability, you too will collect payment directly from the customer. This isn't unusual or exclusive to serving.

So, yes, paying 0% makes sense. Without alcohol being purchased, there is no business relationship with the server. The transaction is clearly with the establishment and the establishment alone. With alcohol, things are less clear cut, but I have never met a server yet that outlines their fee structure. It is generally understood that they are going to do the work for free.