Playing a guitar poorly still sounds quite nice, so the learning process is not so painful for the rest of the family and neighbours. You can play tunes or accompanyments or sing.   
Not many violin teachers are prepared to let the student do this with their violin. I know there is some flexibility - some teachers will teach through jazz or blues if thats what the student likes.
I think the real tradgedy is that in some areas so few children learn any instrument. Its become the preserve of the rich.
FloraG.