.one of the primary tasks of the flight and cabin crew is safety
Agreed
...and the enforcement of the rules and regs......
I think we have a misunderstanding of terminology. At the airline I flew for the FAs just informed the pax of the rules and told them how to comply.
"sit down, fasten your seat belt the sign is on"
Enforcement of the regulation only came if the Captain decided to call the police. I've never seen an FA forcibly remove a passenger or forcibly put the person in his set and fasten the belt.
Sadly a lot of US FAs are on a power trip and love telling people what to do.