I'm an aussie and last year in Australia when my Grandmother died of terminal cancer (we nursed her at home) the palliative care group specifically asked if they could have her left over meds for other needy patients. Even though there were over 100 amps/120mg morph plus amps of midazolam etc etc in boxes untouched the pharmacy was going to destroy them. The pharmacist aslo told us that once the scheduled meds had been dispensed that there was no paperwork on meds that were returned and destroyed - including amps of morph (they could have had one hell of a party at that pharmacy and it does happen!). As the palliative gruop is registered and highly recognised he encouraged us to donate them. might not be legal but at least sensible to recycle at least the unopened meds.
Half the pharmacies in the US remove pills from their oroginal containers into a dispensing container anyway. Theres not much difference than inspecting pills in an open bottle and rebottling them for dispensing.