They shouldn’t request tips at all. Tips only should be provided if a customer feels like the service was above and beyond normal.
That’s not true in the US. They have a tipped minimum wage; there, if you’re not tipping you’re stealing someone’s labour.
It is a sucky system, as the buried lede in that article shows:
However, data from the very checkout system that prompted tipping revealed disparities in pay. Neitzel noticed that Black employees were earning less tips than their White counterparts.
But, until it is burned to the ground, that is the system and (in the US) you should not use it to exploit people.
Sure, but that’s a societal and cultural change. I’m talking about a legal change.
I’m sure the invisible hand of the free market will sort it out and arrive at an optimal solution soon.