In most places, except for Las Vegas, you do get taxed on the table games, especially if you win a large quantity of money.

They just don’t tax you directly on winnings under a certain amount. It is difficult to win that much money on one hand at a table game unless you’re a high roller, whereas on slots your winnings are all at once and easily monitored. You are still legally required to report all winnings as Income (No one does, but…)