Alice, I hope Dick Gaughan won't mind me quoting this, which he posted to uk.music.folk recently:

Opera singers sing in concert halls which are generally
acoustically superb, not rooms with thick carpetted floors, heavy
drape curtains and thick flock wallpaper. And I don't know of any
who do 200+ solo gigs per year where they sing non-stop for around
two hours per night, getting straight up from the floor to perform
cold, without any dressing room facilities to exercise in and do
vocal warm up routines. The rider to an opera singer's contract
would make any folk club organiser have a heart attack - it would
cost more than most folk professionals' entire fee.

So provide me with the average opera singer's working conditions
and environment and I'll sing without PA too.

Anahata (quoting DG)