This is something I think a lot of Americans don't understand about Europe.
In the US - particularly east coast - there's MONTHS of miserably hot weather, like weather that will kill you if you stay out in it too long.
In a large portion of Western Europe, there's probably about 2 or 3 heat waves spread across the summer, and the rest of the summer is quite cool, like cool enough that if you have an AC, you don't run it anyway... So people are lazy and they're like "oh I don't REALLY need that"