They are now, but I was given the reloading inventory of a co-worker's father who died, and there were old rifle primers just loaded full up in a square plain cardboard box.
I only buy CCI, so I do not know about how the other brands are packed.
Black powder primers come in a little tin all mixed together. You can buy them at Walmart but it is absolutely illegal to carry any component used in blackpowder shooting on a plane.
If you buy either powder or primers and have them shipped then you have to pay an extra $20-25 hazmat fee. You can have 50 pound of either shipped but not in the same container.