I don't think you read the article. It explains that those three members who came forward were not actually servers, but restaurant management & owners. Additionally, the article is not missing this issue you call out. The author goes so far as to discuss Casino dealers in Vegas who would stand to gain the most out of this sales tax proposal (sales commissions in your anecdote do not count as tips). But primarily, the author is concerned about the 1/3 of tipped workers who do not pay federal income tax and are at risk of falling below the poverty line due to reductions in their minimum wage.