Children have to put in the hours, maybe the same or slightly less than an adult does, to learn to read music. A 9 year old will need to practice reading and pl

Children have to put in the hours, maybe the same or slightly less than an adult does, to learn to read music. A 9 year old will need to practice reading and playing daily for at least 3 years before they can kinda sorta (sight-)read through beginner material with some facility. Most (middle-class with supportive parents) children who are learning to play an instrument benefit from having the time, space, and energy to do this as a part of their ordinary schooling routine. This is of course in contrast to many adults who have to attend to work, family, and other life things. I started learning to play music as an adult with zero training as a child, and in my observation, adults (such as myself) don't actually have a problem learning sheet music, so long as they're comfortable practicing reading for several years daily, just like a child would. I'm several years in with daily practice, and I can work my way through sight-reading early-intermediate classical repertoire, albeit slowly. Adults, at least those with the privilege of learning music, are usually already quite literate and perhaps even quite formally educated. Moreover, said adults also have a strong conception of music—their ears are good and attuned to their preferred styles of music. To many such adults then, it feels agonizing to start learning to read, and dedicate oneself to the pursuit at a child-level for many years. No doubt plasticity is a factor, but I genuinely think it's grossly overstated.