AFAIK Cargo hooks are certified equipment. Unfortunately they, for some reason, don't seem to get maintained in the same way as the rest of the aircraft. Although technically they should be. In this patch it is entirely feasible to operate over and sling over a built up area. It has happened for years and quite frankly is just not an issue of concern. It is the main operators business (95%) and not just occassional. Subsequently hooks get a lot of attention.
It seems that liability is covered adequately and there are cultural differences. The loads are all attached and rigged under the control of a licensed and trained "Flight Assistant". BTW these guys have an excellent training manual.
Mind you this is in a country where JAR Ops simply would not work and has been observed accordingly as well.
As an aside - next time you work with someone watch the movements of the hook with a Bambi on it especially on release with a little speed or when dropping in the water to pickup. Invariably it can be traced to the manual release cable being restrained too close or tight to the hook. Then again there are other gremlins - had a H300C once which would pickle when you turned on the landing light. EMF and spikes!