Question

Why do windows of distant houses appear to reflect the sun only when rising or setting

Answer 1

Because the sun in the middle of the day, is up above and the windows are lower on the side. When the sun is setting or rising the sun is closer in a way and lower to the windows than before. So the raise of the sun hits more.
I don’t actually know the answer, I just thought of it and think it’s a good answer.

Answer 2

most importantly, the sun is reflected back at the same angle as the angle of incidence, so with vertical panes of glass and the sun overhead, the reflection will just hit the ground before traveling any distance.