A year and a half ago, I read an illuminating book on British politics at the end of the Revolutionary War that first led me to try to answer this question. I've now just finished another excellent book that explains why Britain went to war with the colonies in the first place, Nick Bunker's An Empire on the Edge.
This book is a non-fiction thriller, propelled by a page-turning narrative and enlivened by delicious details. Bunker has also gone through a lot of archival material, especially the formal reports of colonial agents and the family letters of key players. I'm greatly impressed by the breadth of his research and the quality of his writing. No wasted words. No dull digressions.
What I learned from Bunker is that the British government stumbled into war with the colonies, dithering for months at a time and then making tactical decisions unrelated to a strategic plan. I also learned:
-- London was ill-served by its colonial agents. They were slow to report evidence of unrest and were overly optimistic about the loyalty of the locals.
-- Britain paid little attention to the colonies in 1771-74 because it had greater fears of war with France or Sweden or Russia. Those potential conflicts were of much greater concern than the possible loss of the American colonies.
-- The Boston Tea Party was a slow-motion crisis touched off by a glut in the global tea supply and near bankruptcy of the East India Company because of mismanagement. When it occurred, it was treated as an act of treason and rebellion that had to be severely punished to preserve the authority of the King and Parliament.
-- Despite the widespread view that only severe punishment would allow order to be restored, the actual measures before the cabinet and voted by Parliament were often delayed for weeks pending formal legal opinions on whether statements and actions by the colonists constituted treason.
-- The long times needed to transit the Atlantic, ranging from 4 to 7 weeks, caused additional confusion and uncertainty over what was happening at either end.
-- The colonists were not just angry over taxes but over Britain's assertions of sovereignty and retraction of rights they had enjoyed for many years.
Overall, I came away with the feeling that opportunities for reconciliation were missed at various times, so by 1774 both sides had hardened positions and rigid mindsets about each other that made each subsequent move tragically inevitable.