The British army had a large number of soldiers with around 50,000 troops. They also had an additional 30,000 mercenaries on their side. This amount of firepower boosted their confidence.
Sending troops to the colonies was slow
This journey is taking forever...
The British troops were much more experienced in battle. Britain had more time to prepare their troops for war. Some colonists could have had barey any experience with a gun.
Being far away made strategies hard to create
This is a tough call.
Britain has accumulated plenty of resources after many years of being a country and being able to produce these goods. They rarely lacked food, gunpowder, or uniforms. the same cannot be said about the colonists.
The king couldn't convince the public to want war
Why should we spend the money for some little war?
Due to Britain being a faraway country, the journey troops took to America was long. This made it difficult to put pressure on the colonists at once. The colonists used this to their advantage.
Since Britain was located far away, deciding what locations were the best to hold was difficult. they didn't have the information of what places were the most strategic. Often they didn't have the ability to really choose.
The king and parliament werent able to convince the public that they wanted war. They asked if it was worth the money or the danger they would be put in from combat. Few soldiers openly volunteered.