@pmw Canadian Cell Supplies can ship however they choose, and what they do isn't representitive of how Public Mobile themselves ship.
My neighbour have on a trip from public mobile I was there when they picked up the mail it came like @RosieR did. It came in a medium sized envelope with public mobile's logo and design on it and inside the card with the SIM card.
You should report the tampering of your mail to Canada Post. It's uncommon but they do take it seriously and will investigate the matter.
I was planning on doing that as well, however the envelope it was sent in doesn’t have any information stating where it was sent from, also no tracking number. I will be calling my local mail delivery.
I ordered two more SIM cards from Public Mobile (here) a while back. When they were $5 each (plus tax). They arrived through Canada Post after about 5 days. And they've been sitting in my PO box for about a month. Or is it two months now? Oops.
A sealed Public Mobile envelope which contained two of the unsealed foldout cardboards which each contained a SIM card.
(I opened things for this display photo. Low image quality is intentional.)
Other online vendors might use different packaging and different shipping.