We're talking about dash cams here, not body cams. They had TV shows in the 90s based on police chase videos from dash cams. World's Wildest Police Videos first aired in 97, though I suspect there were shows prior to that, the names I cannot recall. So police dash cams have been in the popular culture for almost 20 years. I think cops in Chicago (or any city) knew what they were signing up for at this point.