The olympics don’t take only one day, the paralympics are also a thing, as are the winter olympics. The olympics that happen on leap years are the summer olympics and February isn’t in summer.

Early voting takes longer than a day, and there are elections other than presidential elections that happen with greater frequency.

And February 29 doesn’t happen on years ending in 00 unless the year ends in 000.

EDIT: scroll down to see how confidently wrong I was about leap years!