A tax cut is not actually a government subsidy though. That is an oversimplification. A government subsidy is when public money is SPENT on a good or service

A tax cut is not actually a government subsidy though. That is an oversimplification. A government subsidy is when public money is SPENT on a good or service to artificially encourage investment in it (or someone just has good lobbyists). An income tax cut is reducing the burden businesses and individuals must incur from producing economic value. While taxes and subsidies can both be used by government to encourage selective behavior, they are not the same. They are different instruments and operate differently. You're making the assumption that everything has an immediate effect. Some things incur a cost in the present for a payout in the future. If you go to college for 6 months (the amount of time the tax bill has been in place) and still don't have a degree or job, does that imply that going to college doesn't work? You're also making the assumption that this is a controlled experiment with no other variables. Which is not the case. There are many other things in play.