From pilots I know personally (face to face) there is a very strong correlation between those who do not use the internet, and their age.
They don't need to be much older than me, either. I happen to have been in electronics design since day 1 so I was always "in" this game, but a chap of say 60 who has been insulated from it by doing a job which does not involve email etc communication will not necessarily be up to speed.
This lack of IT literacy is seen in every walk of life and is a real issue for employers, because so many jobs today require the use of email, at least. It is really quite sad sometimes; I had one temp-agency woman of about 60 trying to feed a credit card into a fax machine, to authorise the card. It is unfortunate that working practices (specifically, the use of IT methods) have changed so much faster than many people have been able to cope with.
This incidentally is IMHO who there is so much apparent adult illiteracy around. There has probably not been an actual increase, but a lot of employees who used to do purely manual jobs have been pushed into jobs where they have to do email, etc, and they end up looking ridiculous because they can't write.
And of course about 100% of those who don't use the internet won't be getting notams, because one cannot get notams (practically) otherwise.
Obviously anybody on pprune.org will be on the internet, and some are likely to be offended by this discussion.