I think I shall just end it here before I get into an endless loop.
From my understanding, helmets should compress to slow down the head and crack to dissipate the force.
I believe that all helmets are required to be tested to at least BS EN 1078 in the UK, and I agree that they may not meet up to this standard.
I for one, shall wear a helmet (a new one, not a second hand one) as regardless of how it is tested, it should still reduce some of the impact no matter what. Even if it cracks at 25 Newtons, that is still less of a force that impacts against my skull and so a decreased chance of severe injury.
Anyway, good night.