Canada never agreed to be part of the United States. Of course they would reject the authority of a foreign leader. But Great Britain voluntarily joined the EU. They weren’t subjugated.
This is the part of the Brexit campaign I find most flabbergasting. They talk as if they were invaded by the EU, not as if they willingly agreed to become a member. Fine, you want to revisit the original decision, you are unhappy with membership, fine, withdraw. But please stop talking as if you’re throwing off the shackles of an oppressive invader. It’s not fucking true.