In the UK system, after an election, the party with the most seats, or which can command a majority in other ways, forms a government. Changing the leader does not create a need for another election. I gave you fairly recent examples of this. .

Going further back; Lloyd George took over from Asquith in WWI, and Churchill took over from Chamberlain in WW2, without calling an election.  There are other less well known examples. It's always been accepted in the British system. You are making a fuss over nothing as it just doesn't matter - except to those who are trying to score debating points

I'll repeat, as you don't seem to have grasped it from my first post. The Fixed-term Parliaments Act makes it very difficult for May to call an election should she want to.