It's the same thing with tiny tax cuts. No business person is saying, "I'd love to hire 30 more people to fulfil customer orders, but I need a 2% reduction in my top marginal income tax rate to be able to afford that!" No one pays wages out of their post-tax personal income. Either you have the incoming business to support hiring more people or you don't. If you do, then those wages and employee taxes go in your "costs" column and is a legit business expense you wouldn't pay taxes on.

Yes a tax environment can be oppressive and make hiring unattractive, but that's not what is relevant to those "cut taxes and I'll hire more people" debates. It's pure nonsense. A drop from 42% to 40% top marginal tax rate is not going to kick off a hiring boom.