Almost no countries have a directly-elected chief executive. Certainly that's not the case in the bulk of countries with parliamentary systems. For instance, outside of his own district ("riding", I think they call it there), no Canadian even saw Justin Trudeau on the ballot, and the few who did only saw him as a candidate for Member of Parliament, not Prime Minister.

What typically happens in those countries is that the party hacks of whichever party (or coalition of parties) has a majority get together and decide who's going to be the Big Cheese. The average voter has little or nothing to say about it. Voters who are registered members of the majority party or parties may have a (small) degree of influence, but the ones who belong to other parties don't get a say.

Worse, most Canadian parties actually charge you dues to belong to them (to its credit, Trudeau's party is not one of these). No pay, no say.