I don't necessarily think it is stubbornness, more fatigue. Just as with the responses to the covid pandemic, people get fed up with being constantly blamed for all the ills in the world for simply going about their lives.
Its made all the worse with examples like the one at the end of your post. If energy companies really are cashing in on buying cheaper, greener energy then not passing that on to customers can you really blame anyone for becoming sceptical? As I've said previously, if you want real buy-in then make it affordable.
I did imply that stubborn wasn't really the right definition.
Technically the cost issue is one of the government's making. Historically the cost differences weren't all that big, so if someone was paid 150 when they offered 100 it's not that big a deal. Now if they offered 55 and they get paid 400 that has a big impact on their profits.
If there were tiers of payments so the bottom 1/3 got paid the 34% percentile value, the next 1/3 for paid the 67% percentile value and the last 1/3 for paid the 100% percentile value it would allow for lower energy bills whilst still allowing some extra profits to be generated. It would also require a fairly limited change in how things are done.
I'd say this is pretty key actually. Being told repeatedly how terrible you are by merely existing doesn't exactly motivate. At least when organised religion used to do so it was with the promise of heaven at the end of it! You're always going to get some people deeply devoted to a cause and to embracing personal deprivation as a result - there's more than enough examples of that, most are probably religious in some way - but trying to enforce that on the entire population is very tricky. (Indeed one could easily argue that the response we were told to take to covid, and now net zero, have a great many similarities with a religion (if being polite) or a cult (if being less so!)).
As I've said above though, while they are clearly trying to use the same mechanisms of persuasion and 'nudging' and outright fear-mongering we saw over covid, there are two key differences : the things we were told we had to do, which markedly reduced our quality of life, were supposedly 'very' temporary (although of course they turned out to be less so) and there was a (supposed) immediate consequence of severe illness or death for you or loved ones if you didn't. With net zero, these negative changes are permanent and the consequences for not doing so are abstract and distant. I think that means people are far less likely to go along with net zero than they (regrettably) did, at least for a time, with covid nonsense.
Only there's been significant progress, with scope for significantly more progress, without or significantly harming or quality of life.
Arguably there's elements (such as waking and cycling) where by making changes there can be wider benefits.
By walking/cycling for about 30 minutes a day you meet the World Health Organization's guidance for being baseline healthy. For some, whilst getting to work would take them longer, by removing the need to do exercise outside of travelling thru could actually reduce the time they needed to do both separately (10*10 minute commute plus 4*10 minutes travel to a gym plus 2*1 hour gives a total of 260 minutes, whist 10*25 minutes cycle commuting is a total of 250 minutes).
That's before you consider the fuel savings (if you can reduce the number of cars then the savings could be quite significant with the average cost of car ownership being over £3,000 per year).
Installing solar panels gives a pay back period in energy bills which even for someone in their 60's could be worth doing, and once that's happened it keeps your energy costs reduced.
The thing is, few who don't like the thought of climate change would actually go out of their way to waste money (for example buying a 10 year old fridge rather than a more modern energy efficient one) just to ensure their emissions are higher than needed. Just as in the same way few actually went into COVID wards to prove that it wasn't a thing.
It mostly boils down to how much effort the individual is willing to put into reducing their emissions, for some the answer is no effort (but they won't make an effort to increase our either), for others they'll do everything that they can to cut their emission.
I do like you're analogy of religion, as they be loads who just get in with it, don't make a fuss, might talk about it when asked, etc. They will be embarrassed by those who are loud and obnoxious about it, as they know that it's pouring people off finding out if it's something that they could be interested in. Not least, because those people tend to make a big fuss about something - when actually it's not that big a deal. Often because there's a rule which had been set up (sometimes with good intentions, and often it was useful at a given time but had outlived it's usefulness) but it just upsets people not within the religion when people bang on about it - when the reality is that it's not such as big a deal as people make out.
Clearly the best thing to do to cut emissions is to not drive at all, however you can still get many of the benefits if enough people just reduce their car use by a small amount. If your get told sell your car, it's an instant no I shall not. Hey asked if you'd join a group of neighbours to reduce your average mileage by a bit and the response is likely to be more favourable. It could end up with the same overall impact on emissions (OK you'd probably need about 200 neighbours) but it's impacted you all a lot less.
Even for those who do things which go beyond not making an effort, mostly it's because they aren't willing to make an effort to change something (lights, cars, insulation, etc.).