Why not a postcard for insecure and envelope for secured? Might be hard to distinguish in small icons and can be confused with email too easily but otherwise th

Why not a postcard for insecure and envelope for secured? Might be hard to distinguish in small icons and can be confused with email too easily but otherwise the message should go through. Can't be worse than padlocks with different shades of green as we have today anyway. Does anyone actually understand them? Here on HN i get a gray padlock, on some other site i get a green padlock and on yet another site i get a padlock and a nice fancy badge with the website name in it. Doesn't help that every browser keep changing their looks with regards to this every 6 months also.