cost of flying in Canada is far lower than over here
Not only is the cost of flying in Canada about half what it is in the UK, which one might guess would lead to twice the number of pilots proportionately, but Canada is far larger and there are vast areas of it that can really only be visited by air. The UK has no areas that are essentially inaccessible without a float-equipped Beaver!
So, actually the question is: How come there are so few pilots in Canada?