@Alexandra199
Personally, I agree that 23 is excessive. I used to work for the Energy Saving Trust and we were always trying to get people to set their thermostats to a maximum of 21. For a very well insulated home, or a small, modern apartment, I think you could easily go lower, but then I am British. We don't think it's weird to wear a jumper indoors.
It's not just people from hot countries that have an issue with this (although there are those, e.g. the guy from Florida who demanded I turn the heating on in June because it was raining) but I have found that gets from cooler climates can also have very different views on this.
Almost every German guest I have hosted outside of the summer months has made a fuss about the heating. It's pretty common for them to ask about it as soon as they arrive, even if it's 20 degrees outside. They want it on 'just in case'. Having friends in Germany, I also noticed that it's not unusual there for people to have the heating on 24/7 during October and leave all their windows open at the same time. I have no idea how they can pay their bills. Maybe these price hikes will change this behaviour?
One Russian guest was very surprised that I didn't have the heating on in September (it was pretty warm outside). She told me that in Moscow, everyone automatically put the heating on full on 1st September regardless of the weather. They didn't mind if it got very hot inside because they liked to work around barefoot and in t-shirts. More recently, I had a Polish guest who complained incessantly about being freezing even though everyone else seemed fine and refused to let me check the radiators in his room because he said they were already hot. He also refused extra bedding. I am not sure what he wanted me to do. This surprised me as my Polish friends here in London seem very frugal with the heating.
These were all young people who like to think of themselves as more environmentally aware than previous generations (except for the Russian girl who told me bluntly that in Russia people don't care about that stuff), but it's simply not true. Most of my guests are young and many, many of them only care about the environment if it's no inconvenience to them and doesn't interfere with their lifestyle.
I am not joking when I say that not a single one of my recent or current guests seem aware that there is an energy crisis and these sorts of price hikes going on, and it's all over the newspapers. They look surprised if I mention it, or just blank. I think you are right that it comes down to cost. Once these young folk are paying their own bills, they will think twice. That doesn't help their hosts in the meantime though!