It's just supply and demand. It makes working in these industries relatively more attractive, increasing supply of labour and therefore reducing price of labour. So restaurant owners capture some of the benefits
And because the implication of your argument is we should never tax anything because that's a benefit to both the consumer and the business
To me, the bad part is the tax reductions only appear in behavior I don't agree with: high overtime and tipping (when it's semi mandatory).
I'm not American, but this is also showing up in my country.