The GOP believes in small government and the free market. They don't like income distribution because they perceive the poor as unworthy.
 
Any tax cuts in the US are gong to benefit the wealthier segment of the population because like Canada the to 10% pays most of the taxes. 
Given that the wealthy in the US are way more wealthy than those in Canada their taxes generate considerably more in tax revenue.
Remember their "rich" are like the Kardashians while our "rich" are doctors. Not even close.