The difference is NVidia probably went through the game with a fine tooth comb ironing out any such issues with PCSS, AMD are probably still lamenting even having to get involved in adding their technology to a game it's such an inconvenience to them. Lazy developer etc.
Are you kidding? AMD has had it spot on and had far less issues when the game come out even with dual cards.
From my opinion Nvidia was the worst option and didnt look like realistic shadows at all just a opaque blury dark shadow which was really soft and blury. Im on holiday right now and I can tell you shadows are not soft and blury in daylight. They are sharp even when moving such as blowing branches. Not say AMD was better but it looked better as in more in the right direction. Rockstars shadows were spot on for me just could do with making them shadows not look so deep and dark in daylight as closer to a lighter black than a deep dark one.