This is likely simply due to the fact that more homes have AC now: ... "By 1980 that number had risen to 63%, and in the 40 years since then air conditioning h

This is likely simply due to the fact that more homes have AC now: ... "By 1980 that number had risen to 63%, and in the 40 years since then air conditioning has grown exponentially and is now present in a whopping 95% of homes in the US according to the most recent US Census." https://www.fixr.com/blog/2021/06/22/presence-of-air-conditioning/ https://www.fixr.com/blog/2021/06/22/presence-of-air-conditi... You might say that this is because we need it more now, but I think it's actually just that we can afford to install it now in every new home and so we do. It's just considered standard equipment.