The profit from the American colonies came mostly from the food that was exported to the more lucrative Caribbean islands, and the lumber industry, which was needed for the ships.

The English tax system itself had trouble taxing America, because Americans didn't have enough gold or silver to make that easy, and customs officials in America were practically on their own, which made them easy to threaten.

The only practical method of tax was thus forcing all goods to come in and out of Britian, which probably caused more problems than it solved.