If every bar reflects the same proportion of the population then that would mean every bar of the histogram would have exactly the same height, because the y ax

If every bar reflects the same proportion of the population then that would mean every bar of the histogram would have exactly the same height, because the y axis on a histogram is density or proportion. I don't get how you can be so confident about a concept you only vaguely remember from a class you took long ago, and that even after reading the relevant article on wikipedia you conclude that therefore wikipedia must be wrong rather than thinking "hmm, wonder whether I'm misremembering things here..."