The tipping system still baffles me (and I never know when I am supposed to tip or not .. )

From what I gathered, it comes from the prohibition as a way to supplement hotels and restaurants personnel wages (since they were making less in that context).

Why it persisted to nowadays and has been extended to many service works baffles me to no end.

Taxes are also added at checkout when you buy e.g. groceries, so it seems pretty cultural to have a very opaque 'what you pay' system.