Some moulded-on NEMA plugs have thick strong pins (same as the Australian counterparts) made of solid brass (or iron) that you cannot bend at all with your bare fingers without damaging the rubber or plastic housing.

Others are folded brass pieces that can bend into odd shapes. It all depends on the (usually Chinese) manufacturer of the cordset. It seems like the folded brass blades are more common though. [Linked Image]

Also, some replacement plugs have thick, non bendable brass solid blades and others have what are called "spring-action" folded brass blades which because they're flexible, are supposed to make better contact with the receptacle contacts.