The primary source of anger and resentment among American colonists regarding British taxes was the lack of political representation. The colonists did not have any direct representation in the British Parliament, which made decisions about taxes and other policies that affected them directly. They believed that taxation without representation was a violation of their rights as British subjects and a form of tyranny. This discontentment was famously expressed in the slogan, "No taxation without representation."
The American colonists argued that they should have a say in how they were governed and how their money was spent. They felt that they were being treated as subjects rather than citizens and that their interests were being disregarded by the British government. The lack of political representation was seen as a fundamental issue of fairness and justice and played a significant role in fueling the growing tensions and eventually led to the American Revolution.