Somebody could have shipped it to them in a way that they knew would be detected. Or not.
If they had really want to do some police work, they could have opened the package, substituted oregano for the MJ, tapped the mayor’s and his family’s phones, then sat back and waited to see who one of them contacted about the screw up.
Or maybe I’ve watched too many cop shows on TV.
Besides, how many people would NOT bring a FedEx/UPS package sitting on their front porch into the house, whether they could remember ordering something or not? It is not suspicious or unusual behavior, and does not indicate intent.
The person in charge of calling for this raid is an idiot.