I am so sorry to hear how some of you got ripped off.
Here is how you can protect yourself in the future: As others mentioned, when ordering something, insist on using US Postal Service
https://www.uspis.gov/ for any correspondence, check mailing and shipping. If corresponding through e-mail, insist on conformation that goods will be shipped using US Postal Service. As far as I know, committing crime using US Postal Service is federal offense, and postal inspectors have legal power almost like FBI agents.
"Our jurisdiction is worldwide" see more
https://www.uspis.gov/about/what-we-do
Also, see this:
Enforcing Federal Statutes
If it has anything to do with preserving the safety, security, and integrity of the nation's mail system from criminal misuse, we do it. Our Postal Inspectors are federal law enforcement officers who carry firearms, make arrests, execute federal search warrants, and serve subpoenas. Over 1200 Inspectors enforce roughly 200 federal laws covering crimes that include fraudulent use of the U.S. Mail® and the postal system.
Investigating Postal Crimes
Postal Inspectors investigate any crime with a nexus to the mail. These crimes include mail theft, mail fraud, financial fraud, identity theft, robberies and burglaries of postal facilities, assaults and threats on postal employees, investigations of dangerous and prohibited mails, narcotics, cybercrime and much more.
Once an investigation is underway, Postal Inspectors present the case to prosecutors from the U.S. Attorney's Office and local prosecutors. Throughout the prosecution, Postal Inspectors and other Postal Inspection Service employees can be called to provide testimony and explain their findings, process, and conclusions.
Etc., see more here
https://www.uspis.gov/about/how-we-do-it
Also, according to this
https://www.houstoncrimedefense.com/mail-fraud-using-fedex-ups-houston-texas/ :
Mail fraud is a federal offense in which an individual uses the United States Postal Service or a private carrier to commit fraud. The fraud can be to either obtain money or property under false pretenses or distribute counterfeit funds. While private carriers are not owned by the government, it is still illegal to use private carriers, such as FedEx or UPS to commit mail fraud.
The only problem is that, as far as I know, private carriers do not have any inspectors to crack down on criminals like US Postal Service inspectors do.
In other words, many companies and individuals are using private carriers, so if something goes wrong, there is little we as individuals can do. If something goes wrong using US Postal Service, those responsible are on the hook, and will have postal inspectors asking some tough questions.
Please correct me if I am wrong.
Also, if you live in Canada, and using private carriers for ground shipping from USA, in order to reduce shipping cost by the air, there is a good chance you might be hit with brokerage fees when receiving parcel. First hand experience! When I asked how that could be, I was told that brokerage fees are waived when parcel is shipped by air. Later I learned that Using US Postal Service these brokerage fees are not charged, probably because parcel in Canada will be delivered by Canada Post, and they do not charge brokerage fees.