But in Bulgaria you need one during at least the whole summer and I suspect also a bit longer, while in Czechia you could have gone without one the whole year and really need one only for a week or two in the summer. So most people didn't think it was worth the expense. Now that's changed and the attitude will change too.

In my newish (25y old, well insulated) flat we really started to feel the need to get one only 2-3 years ago. Until then it was nice to have but not necesarry.