but nobody is saying tipping is, or should be, a solution to low wages.

The man being interviewed in the article is literally making this exact argument.

Recognizing that the act of asking for an unsolicited tip as a requisite part of buying a coffee is making both customers and himself uncomfortable, acknowledging that his take home pay is so abysmally low that he depends on tips to make a living, and then after all of that, blaming the customer as the primary problem for not being willing to tip in the current economy/environment, is like making a 95 yard run and then tripping over your own shoelaces at the endzone.