I wouldn't want any elderly person I knew walking that distance in any of the 3 weeks Phoenix typically spends over 100 degrees (even hotter over pavement).

100 yards is less than a block. Did you mean to say a longer distance?

And yeah, walkable cities includes infrastructure that does not magnify the sun at pedestrians (see: shade, plants)

You know what desert cultures around the world do to avoid this phenomenon? They just go outside in the mornings and evenings.