Because there are low-tech ways of dealing with the cold: thicker clothing, resistive electric heaters, fire. With heatwaves past a certain point, you need high-tech (read: expensive) air conditioners, which is out of reach of tons of people.
Historically, the only reason more people died from the cold was because it was really cold in places where a lot of humans live more often than it was really hot. With the Climate Crisis, that is about to flip around.
Staying inside wouldn’t matter if you didn’t have air conditioning and the juice to power it.
However, there are home designs which naturally cool themselves and/or divert the high heat away from the dwelling areas. I have not seen many of those built in the USA, especially not in Florida.
Yeah, but I’m talking about Florida. Everyone here has air conditioning. The people that don’t have the money to power air conditioning usually north to some place cheaper.
Its not about the ability to pay for it, its about the fact that the resources to constantly power air conditioning year around are finite, and will eventually run out.