You might be interested in this answer by /u/Jordan42.

As /u/thefourthmaninaboat mentioned, this is an incredibly difficult question to answer because it is essentially a hypothetical in many ways. However, that said, I will provide an answer that will discuss some of these factors.

I'm going to provide some more information in addition to /u/Jordan42 's answer that /u/Aetol provided.

This question makes the assumption that the British didn't offer representation to the American Colonies, so we should start there. This assumption is flawed because there were people who did consider this a viable option in the late 1770s.

The Carlisle Commission was a group of British negotiators sent on the behalf of the British government to seek a cessation to hostilities and create reconciliation between the two sides during the American Revolution. The negotiators met with the Continental Congress in 1778 and attempted to get the United States Congress to end the war with a truce under an agreement of self-government. This self-government would have theoretically empowered the colonies to select their own leaders, at least in their own territories. Now it must be stated that this offer came about 3 years after the first military engagements happened between the two sides, so it was a little late in many ways.

The commission was led by Admiral Lord Richard Howe who had been ordered to not be a "destroyer" but rather a "mediator". They met with several members of the Continental Congress, but the meeting was largely a failure for several reasons. Arguably, the major problem was that since Parliament refused to acknowledge the United States as an independent entity from the start. Howes' refusal to acknowledge the Congressmen as working on the behalf of a separate nation caused immediate tension between the parties. The Continental Congress demanded to be viewed as a legitimate governing force, which most British leaders refused to do from the start. The agreement also faced other issues, such as some of the British negotiators being accused of trying to bribe some of the delegates of congress to agreeing to the terms. (Specifically, Robert Morris and Joseph Reed were two that were known at the time. Chris Coelho, Timothy Matlack, Scribe of the Declaration of Independence, McFarland Publishing, 2013. PP 111 )

Included in the deal was some semblance of self-government and some representation within Parliament, however most delegates did not find the terms appealing. This is partly due to the fact that by 1778, The United States was healing from their embarrassing losses of 1776 and failures of 1777. The Battle of Saratoga had breathed new life into the rebellion, possibly persuading France to lean even further towards towards joining the Americans in their war. So the Continentals were not quick to accept the terms. The Continental Congress wanted independent rule set aside from Great Britain, which the commission members were not empowered to grant. Also, aligned with this was fears that the offer would not actually be carried out with on the British side. Most of the American representatives guessed (correctly) that the British motivation was to prevent an American-Franco alliance, which they were on the verge of creating. Here is how one historian explained it:

The Continental Congress ultimately responded with saying, "The Continental Congress declares that “the United States cannot hold with propriety any conference or treaty with any commissioners on the part of Great Britain unless they as a preliminary thereto, either withdraw their fleets and armies or else in positive and express terms acknowledge of the said states."

Great Britain obviously refused this deal since the representatives had no such authority to end hostilities. Regardless, the commission spent a comparatively short amount of time with them in Pennsylvania before being dismissed.

It is also worth addressing why the British didn't do this early. First, very few people believed that the American colonies could contend with the breadth of the British Empire. The British military was by far the strongest military force in the world, and no one thought they American Colonies had any chance of posing a significant chance at rebelling against the empire. By 1778, so much had changed that contemplating a negotiation made sense to some people.

On the flip side, most British leaders viewed the Americans as petulant children who did not deserve representation. King George, who wasn't the most stable monarch, represented this idea when the described the contention with the colonies as,"Once vigorous measures appear to be the only means left of bringing the Americans to a due submission to the mother country, the colonies will submit." It was believed that this was a lose - lose scenario for the Americans, and that a good whipping, as a parent did to a disobedient child, then the mother country would remain victorious. By 1778, the narrative had changed. America had survived 3 years of war and now had a trained army that could gain victories. They also were forming an alliance with France, who was now sending supplies to the colonies. More-so, American leaders were no longer desperate for the British to come to the negotiating table, which was their initial goal if you go back as far as 1774 or earlier.

Hey there,

Just to let you know, your question is fine, and we're letting it stand. However, you should be aware that questions framed as 'Why didn't X do Y' relatively often don't get an answer that meets our standards (in our experience as moderators). There are a few reasons for this. Firstly, it often can be difficult to prove the counterfactual: historians know much more about what happened than what might have happened. Secondly, 'why didn't X do Y' questions are sometimes phrased in an ahistorical way. It's worth remembering that people in the past couldn't see into the future, and they generally didn't have all the information we now have about their situations; things that look obvious now didn't necessarily look that way at the time.

If you end up not getting a response after a day or two, consider asking a new question focusing instead on why what happened did happen (rather than why what didn't happen didn't happen) - this kind of question is more likely to get a response in our experience. Hope this helps!