For my last house, I had spent years on smart home automation, I had a binder that contained clear instructions I wrote for everything, and receipts for every upgrade I ever made on the home, warranty docs, QR codes to download smart home apps to control the devices, plot maps, floor plans, a 1-page list of repairmen for everything- you name it. I made short YouTube videos for everything like turning the water on/off…
For a fair part of the population, especially those using at home a crappy PC crashing twice a week, 'smart home stuff' means that some bug or backdoor may lead them into a mess: lock them out, let an intruder in, over/under-heat for weeks while they are out of town... They don't want any part of this.
Of course there are available possibilities to take somehow full control of your automation with some Home Assistant or the likes but honestly, it’s really not that easy if you are not already a tinkerer.
Great automation will also require more work and knowledge. As soon as you start playing with heating or venting, you are doing work that could require some background. It’s something to buy a nice smart thermostat, but it’s something else to understand where you may place it, how you may program it …
It’s an interesting topic for those who like to tinker, but it’s very understandable that most people aren’t going to invest their time on it.