Canada may be different as there were concerns as to how committed the militia would be...until General Hull who performed so gutlessly at Detroit went far out of his way to antagonize them.
For instance, threatening vicious treatment of any Canadian militia fighting alongside the Indians, as if the militia would have veto power over senior British officers.
You might have London genuinely wondering how dependable the Canadians were, sans the proof of 1812, but without further war between London and DC this simply fades away by, say, the 1830s.
Were there any negotiations before then that might have seen slightly different decisions by London?
The US Army went from @2700 to @6300 between 1807 and 1812. It never passed 65,000, even on paper, during the war, which amounts to less than one percent of the total population. In comparison, in 1861 the US Army was 16,000 and 25,000 in 1898!