Why are liberals so ignorant of a free market currency system that benefits the middle class?

if you want the banking cartels out of business that literally enslave the people by not allowing enough base money in circulation to pay back the interest all the money loaned out why do liberals not support allowing the market to choose what is money. Today if you use something other than the dollar as currency you will be put in jail. This would immediately put an end to the wealth transfer from the banking cartels and restore the middle class.