I work in a hospital and once asked A Hubble rep.Turns out any manufacturer who makes Hospital grade plugs and recepticals install the bumps on the receptical springs and holes on the plug prongs in order to raise the tension needed to separate the two
He went on to say that hospital grade and spec grade cord caps and recepicals are made on the same assembly line.
Instead of sample testing one in every batch for acceptable tension all get tested and any that require 15in/lbs or more to remove get sent on to have the hospital grade green dot installed and price jacked up.It also helps remove the "slop factor" inharent to all mass produced products where everything averages out but are never exactly the same.
We actually have Hubbel meters(modified fish scales)with which we test every plug in the hospital once a year
I have also seen inspectors put the red tag on them for unapproved equipment.This way we cant say we didn't see it's $5000 to the person who plugs it in.
