I did not know Bhutan, or Thailand had referenda on the composition of their government and decided to stay monarchic. Last time they asked in Norway it was roughly 120 years ago, around the time the Model T was all the rage. Things have change a tiny bit since then.
I never mentioned anything about referenda. Popular opinion in those countries is they are largely happy enough with their monarchy.
From what I can tell, in Norway it does seem that things have changed only a little bit.
Note I'm not a particular fan of any monarchy, but you did state that "I think the vast majority of people in any country would prefer a Head of State that is chosen by popular vote rather than by Royal Sperm." That's an easily falsifiable statement.
Most countries where a referendum has been held (particularly in the last 100 years) have decided to go with an elected head of stated, not a monarch. (https://en.wikipedia.org/wiki/List_of_monarchy_referendums)