Re: It's not "why", it's "how"
"To be fair, neither of them were. What people don't understand is that they don't vote for a PM they vote for a party, but the political system has become so personality driven it's hard to see the difference. Once the leader of the elected party steps aside the party can choose a successor, its just that if it happens to be in government we end up with a new PM."
Exactly my point. We never vote for a Prime Minister unless we happen to live in the party leaders constituency, they win, they retain the leadership AND the head of state invites said leader to form a government. There has been at least one instance in the past where the monarch chose a person not even elected to Parliament and asked him to form a government, which he did, and therefore was truly an unelected Prime Minister.