Experienced this literally when my grandparents said "come back and eat here, you are not a baby".

I had very good reasons not to eat, they just can't comprehend this anymore.

As a parent who also has some younger friends, maturity is more about decision making skills, particularly under pressure. When SHTF do they shut down or do they figure out how to move forwards? Do they call for help when out of their depth or do they just flail and make things worse? Do they step up and do what needs to be done to get things going in the right direction or do they just let problems compound until it's a bigger challenge? This is maturity. Being able to figure out what you need to do and then doing it, and adjusting when things don't go how you expected is maturity.

Immaturity is being unable to step up when the time demands it. Unable to comprehend when to take something seriously vs what you can blow it off. For example, interpreting maturity as purely "societal expectations" is indicative of immaturity