What pisses me off with crib sheets is that it's more often than not that it's youngsters who use them

That's not what I see - the older the singer, the more likely they are to use notation (badly), and the larger and more disorganized their song folder is likely to be. The folk scene has not done very well at helping people bow out gracefully.

Here in England there has been a significant growth in ukulele groups (and community choirs) at the same time as folk clubs have declined. There can be between 10 and 50 people playing together, possibly 20 songs in an evening from songbooks containing up to a hundred songs.

They use iPads here. This kind of thing goes back to the "community song" movement of the 20s, and there's no sensible alternative to singing off a sheet. There's a reason why the News Chronicle songbook sold as well as it did.

I belong to something a bit like that, a fluid group of 10-20 people doing Greek and Middle Eastern music. The instrumentalists (including me) memorize the songs quickly. The singers are pretty stuck, because they have five different first languages and share songs. The timescale involved in putting together a set for a new performance just doesn't allow the time for them all to memorize all the material in unfamiliar languages.