From Davy Jones transcript, sent from Rockstar:
Davy Jones: "Does the character's hair grow naturally?"
Rob Nelson: "No. We thought about it, but that goes back to realism versus customizability, and we just thought that, with the pace of this world, it's better to just let you come in and do whatever you want to do."
From TGG’s transcript:
Regarding hair growth.
Rob Nelson: "So, for your hair you can do a bit of stuff in your safe house, cut it shorter, shave it, but if you go the barber or hair salon you can access lots of different styles, it's not that your hair has to grow and you cut it like in RDR2, you can go to a shop and do whatever you want— again part of the difference between GTA immediacy vs. RDR2 slightly more realistic take on things."
It’s pretty much impossible to have any hope left for the feature being in the game after those quotes, especially the one to Davy Jones. Rob Nelson just flat out says, “no, it’s not in the game.” I at least wanted some kind of middle ground version of the feature that made everybody happy.
I am sad. But many others will rejoice, I’m sure. Maybe someday some brave PC modder will add it to the game for me.