I've never seen anyone spot a ball for any reason in bar pool. I always assumed it was because on a bar table, you cannot retrieve a pocketed ball, it's inside the table.
But, actually, your mention would be another solution to being penalized heavily from your opponent's scratch.
This thread is about 8-ball, the only game played around here.
There is one Bar in my area that in their Friday night tournament, to appease the BCA players, they spot the eight ball if your opponent scratches and your Eight ball is behind the line.