I am not up to speed about whether tips are taxed the same as wages or not. I assume the way some hotels add a massive "resort fee" to a low hotel rate means that the "resort fee" is not taxed?
Of course tips are taxed. In fact some states force servers to pay taxes on 15% of their receipts, if they get a tip or not.
Kind of unfair but I guess it also discourages cheating.