Back in the day this used to happen all the time. People would get their weed shipments stolen left and right, because it was so illegal, nobody was going to call the cops on them.
Lots of stories from friends who said they shipped weed through UPS and FedEx that just never showed up. Same for USPS. I think there are people at all of these logistics companies who are dishonest and will rip someone off if they think they can get away with it.
This includes seeds, clones, anything to do with growing weed, etc.
But for it to make it all the way to your mailbox in that condition without some sort of attempt to close it or put a note on it saying it was damaged in transit, tells me something shady is definitely going on.