Probably because it'd be confusing for them, since we don't have the same Thanksgivings: our American Thanksgiving falls on the last Thursday of November, and we remember the pilgrims arriving on the new land, and the natives sharing what they had with them, including the first Thanksgiving feast; their Canadian Thanksgiving is like the first Monday of October, and I forget how they celebrate it, but I don't believe pilgrims and indians are involved.