Well they are trained to 'go' before working and the owner will hopefully have a sighted person to 'pick up' if they are lucky.
My dearest friend was a GD owner until her death nearly 18 months ago.
I think she might have laughed at some of your suggestions - not the easiest thing for a blind person to do although my lovely friend managed to do just about everything independantly
I think there are a lot of sighted people who seem blind when it comes to picking up after their dogs - she would have agreed with that one too