Stilly, there are two reasons why choirs still use music printed on paper.

The first is copyright — PDFs circulate and reproduce faster than bunny-rabbits, and the copyright owner doesn’t get paid. Ever.

The second is singers’ notes — the conductor wants the crescendo to begin precisely here and the ritardando to end precisely there, and he doesn’t like the forte marked for that passage so please change that to mezzo-forte. And don’t you dare breathe before bar 78. Tablet technology has yet to evolve to that level of subtlety, but every chorister has a pencil (never a pen!) tucked behind an ear.

The musicians who use tablets are soloists, like your piano guy, or people who don’t require a tight ensemble to make their performance work. Without a very tight ensemble, a 70-voice choir is a braying mob.