I have that impression too (most students from the local area). This is why I compare it to US state flagships. Most are primarily filled with students from that state. Some differences in that few are in major cities like those three Canadian universities are. And you have the effect of some kids in California preferring Michigan over less prestigious UCs for eaxmple, for which there probably isn’t a Canadian equivalent.
But I think the original statement that in state admission into state schools is mostly straightforward is still true.