Each country's constitution and way of choosing its rulers is different.
It's much easier for a centralized state such as France to choose its ruler by universal suffrage than in federal countries such as Great Britain, the US or Germany.
In the US the constitution was written after a long process of trying to reconcile incompatible views from many states with very different populations, religions, traditions and political views. It was also to satisfy both those who wanted a constitutionnal and federal state and those who wanted the US to be a strong and centralized state.
In France the country is centralized as a result of centuries of patient efforts from the kings of France to expand their power and territory, because France was an exposed country with very frequent wars and invasions over the centuries and that a strong state with one unique and organised army became clearly the best mean to respond to that; because of Richelieux and Louis XIV who wanted to increase the king's power in order to better carry the economy, political power and military might, of Napoleon, the Vth republic constitution, etc..