The central argument of the American colonists against the Stamp Act that is not understood by the writer is:
that it is not the amount of tax that is the problem but rather the fact that the colonists were not involved in passing the tax.
This reflects the colonists' belief in "no taxation without representation," which asserts that it is unjust to impose taxes without the consent of those being taxed. The writer seems to focus on the size of the duties rather than the principle of representation in governance.