re: Why aren't white shingle or light colored roofs more common in the South and hot climates?

The home I grew up in the early 70’s had been built by a doctor in our town. It had a white roof that was some kind of a hard grout or something. It came in 5 gallon buckets and you spread it over the roof and it would dry hard. It was pure white. It seemed pretty durable because I would get on the roof pretty regularly to get stuff off of it or just for the shite of it. We did have to wash it yearly with bleach if I remember correctly.

It was chalky and you could break it though.