My guess is it was a switch someone installed to turn those lights behind the grille on and off and first thought seeing those is someone installed them because they thought it looked cool not that they were hidden police lights.

Police cars back then hardly ever had power widows. Most didn't even have AC and they also usually didn't have cruise. To me it seems more like someone wanted a base car to make it more affordable or because it was lighter but wanted a few of the conveniences.