Running on glass

I went out on a run today and I ran through the city streets. The street was completely empty but there was so many broken pieces of glass. They were small, but glass is glass.
Well I ran and ran thinking my feet would bleed, but when I checked, my feet were perfect. They had no scratches.
The fact that I ran light and with an OK form, my feet didnt have much friction with the ground, making it so the glass wouldnt cut me.
Little glass= Sketchy.
Big glass= NO