It's funny though how different people respond to learning music theory differently. I started on guitar when I was 19. I played for a long time at campfire level. When my kids started learning music I also learnt a lot, and now I know scale shapes and modes on guitar, so I can reasonably play to a song I'm hearing for the first time, then figure it out by ear. But I just cannot make the leap to knowing the notes at each position. I can read music, very slowly, to play on piano, but fluency has never clicked for me even though I've put the time in.
My 8 year old hardly ever practices but just looks at the music and knows the notes on piano and violin.
In any case, I agree that this isn't that helpful to being able to play, it's just an interesting way to understand why things are as they are.
Your kid might have absolute pitch. Only a few percent of people have it.
https://www.youtube.com/watch?v=t3Cb1qwCUvI
Perfect pitch is not correlated with the ability to see written notes and immediately know how to play them on any instrument. It is only barely correlated with the same but for singing the note.
I do not have perfect pitch, but I could always do what GP's kid does. I am now a pretty good amateur singer.
What matters for this is learning to read the music notation and developing a sense (mostly subconscious) of scales and harmony. Perfect pitch does not help either of those things.
Oh right, I misread. GP is talking about reading, not listening.
I think it gets significantly harder to learn new things as you age. It could make sense though like its significantly easier to learn a new language as a child than an adult, something simillar could apply to sheet music also i guess where they are naturally more intuined with its language vrs you who has to kinda use a dictionary for time to time because the "normal" way for you to speak has been so different for so long. But for your child, its another form of expression almost. Its really good to get kids into music while they are young imo