I believe it's been shown at least in the US that most hair donation is dubious in value and some are outright scams. It is one of the ideas that has gotten a "feel good free ride" from the media.
Hair donation is not vital to survival of someone. I always say 'I'd rather donate my blood. That's far more useful than a wig imho" I will often have other comments like 'why don't you donate your kidney?". When they look shocked, and say it's not the same thing, I'm like 'you have two, isn't that kind of selfish?" and walk away. I HATE people who think that if you have long hair, it's your 'duty' to donate it to a charity that, very often, is a scam. Locks of Love has been proven to sell hair donated, that is not usable, and use the money towards 'business needs'. Uh huh. :/