Yes, Granny would be stumped by the lack of good hard boots, but she's also all about practicality and those sneakers look well worn, and practical for the climate. Also there's good, hard rock underfoot, you can grow good witches on hard rock.
I think once the temperature is higher than body temperature you want something that radiates the maximum amount of heat. But I've seen studies that seem to imply it doesn't matter which color you wear.
If it works im curious why only female herders use it. Are the male herders like super chad. What! to hot for you. gotta wear the girls hat. Its not even hot today. Its like only 103.