Why didn't more British colonies join in the american revolution? Did they not have the same taxes, were they not as integrated with the 13?
There were four northern colonies colonies: Newfoundland, Prince Edward Island Nova Scotia, and Canada (at the time Southern Quebec, Southern Ontario only had a few settlements around military posts prior to the immigration of Loyalists).
Newfoundland, was sparsely populated and did not have any incentive to join the US. Its ties were far closer to Britain than the rebellious colonies.
PEI was in a similar position to Newfoundland being quite small and surrounded by British colonies as well as facing many of the same demographics of Nova Scotia with recent British immigration.
Canada was primarily French speaking and the British authorities had gone to great lengths to keep them happy specifically for this purpose. That said, the people were relatively receptive of the Americans to start with (indifferent may be the better term), but a combnination of anti-French and anti-Catholic sentiment with heavy handed governance of occupied territories pushed most of the people back to the British.
Nova Scotia (at the time also including New Brunswick) was the prime candidate for the 14th colony. It was well developed, had close ties with Massachusetts (having been a part of Massachusetts in the early 18th century) and other colonies to the south. A significant number of people from other colonies moved to Nova Scotia during and after the various wars. However, at the same time there had been large scale Scottish immigration immediately prior to the revolution, a significant population of soldiers during the wars also ended up in Nova Scotia. Also important were that the British had a very strong military presence in Halifax and a significant number of loyalists migrated to Nova Scotia. There were a number of armed uprisings attemptinmg to join the larger revolution but the failed.
In addition, although there was an agreement to invite Quebec, Nova Scotial and PEI to the Continental Congress, only Quebec was invited and chose not to send a representative.
As for why the southern colonies (the Floridas and Caribbean islands) did not join, the Floridas would have been in a similar boat to Newfoundland and the Caribbean islands would primarily have consisted of slaves and plantation owners who had maintained their ties to Britain rather than establishing strong local societies.