It’s really sad to me that Americans get put in the awful position of choosing between tipping, which supports the low wages, and taking responsibility for ensuring another human being has a living wage. It’s just such a terrible position for a consumer to be placed in, having to make ethical and moral choices about how much money to pay for goods and services.
We were taught a similar trick in physics - point your right-hand thumb in the direction that current (or electrons, same same) is travelling and the curling of your fingers shows the direction of the resultant magnetic field that the current creates.