Throughout the last six seasons of The Walking Dead there have been many characters to grow in confidence and ability, but physically none have grown quite as much as Carl Grimes.
Despite starting out as a rather annoying little kid, by Season 6 Carl has totally turned the audience opinion, and is now a much loved character and asset to Rick's crew. However, there is one aspect of Carl that still enrages many Walking Dead fans: his long hair.
During Season 5 and 6, hopes were high that Jessie Anderson might give Carl's hair a trim after she cut both her son, Ron's hair as well as Rick's, but alas it was not to be and after Jessie's death Alexandria lost its main hairstylist (though to be fair, Enid did a decent job with Maggie).
However, the rather insightful Redditor SSparkie has offered a reason for Carl's long locks, and to be honest it's kind of heartbreaking. Now, obviously after Carl's eye injury in Season 6, Carl's long hair can now be used to hide his scar, but let's cast the practical reason aside for now, and focus on this theory (besides, Carl was growing his hair long before he had his eye shot out).
Back in Season 1, Episode 3 we saw Carl getting a haircut from his mom, Lori. As the youngster fidgets in his seat, Lori tells him to sit still, before Shane pipes up and tells him "You think this is bad, wait till you start shaving. That stings. That day comes, you'll be wishing for one of your mama's haircuts." To which little Carl replies "I'll believe that when I see it."
But then of course two seasons later, Lori died in the bowels of the prison after an emergency C-section. And, suddenly the day when Carl would miss his mother's haircuts arrived, but it was long before he needed to start shaving.
So basically, the reason that Carl opts not to have his haircut — even though several characters having their hair cut onscreen — is for sentimental reasons. Despite the fact that Carl is now a staunch, zombie-killing, Negan-facing, one-eyed bad ass, deep down he's still just a kid who really misses his mom and the time they used to spend together when she would cut his hair - despite all the fidgeting.