"Who uses major 7ths?
Neither you nor I
But clever dick guitarists
Always seem to try."

Well if you read
my thread (gawd, now he's doin' it too!) I explain that for 'folk music', you can 'fake it' on the Piano Accordion by not having a &th row - you can just play the normal (usually Vth) chord, i.e. a G Maj chord for the C V7 one (which is actually G7). I also point out that if the 7th is really important or necessary, then somebody is probably playing it in the melody anyway!

Actually, getting back to the the title of this thread, perhaps this is why the audience has gone home.... :-P

:-)