As it is openly stated that it will not be carried by FedEx, it’s no stretch that the police will consider it contraband.

It is a stretch. Enforcing contractual agreements is not the job of the police. And it’s also a stretch to say the police are looking to protect the contractual interests of FedEx.

It’s also strangely inconsistent with FedEx’s anything goes practices, whereby FedEx is known for shipping morally dubious payloads:

• #sharkFins (illegal in countries that have a shred of respect animal welfare and the environment)
• hunting trophies
• slave dolphins

Normally, FedEx could normally claim that they are simply maximizing the bottom line in their duty to their greedy shareholders. But the cash ban is not consistent with that. Unless FedEx believes that anyone who loses an insured pkg would claim the pkg included cash as a way to max out the insurance payout. But in that case, it is not in FedEx’s business interest to enforce the policy -- just to be able to point to the policy when an insurance claimant say cash was lost.

(update) In fact, police are preventing crime prevention by grabbing the cash. This inspired me to propose a new rule.