> The poor don't pay any federal taxes at all so you can't give them a tax cut

Even if we exclude poor there are many options how to split taxes between different income brackets, how to tax salaries vs capital gain, how to split taxes between individuals and businesses, how to avoid loopholes e. t. c. (e. g. in the UK I see small business struggling because of rising taxes while multinationals pay little taxes by moving profits offshore and reporting no profits in the UK).