But Canada is gigantic! Other than Niagara Falls, the tourist attractions are either in nature and not world famous (no Instagram-pressure to pick any particular place), in big, modern cities and not particularly focussed to one place (Montreal, Toronto), in old cities where people don't live (centre of Quebec), or in places like ski resorts where if all the hotels are full, it's full.
Amsterdam is large, but everyone only wants to go to the centre, which has mediaeval-size streets. In Barcelona there are a few expected sights. Both cities are also normal cities.
27 million tourists to Canada — 82 million to Spain — 17 million to the Netherlands
https://en.wikipedia.org/wiki/Tourism_in_Canada and similar.