Income tax did not exist at the time of founding. The freedom to spend freely from the fruits of one's labor has been lost.
On your particular example, there are lots of debates to be had about forms of taxation and which kinds are ‘fairer’ - but more importantly, and more overwhelmingly: eighteen percent of the population of America was literally owned by other people in 1790. They couldn’t ‘spend freely from the fruits of one's labor’ to any extent at all.