What is it with the idea that children have little or no responsibility and adults do?
Maybe it works that way when you have children of your own, and maybe a driver's license or work as a police officer or a soldier or a medic, but otherwise I don't much detect it much with folks rather than going to work on time and not dating their coworkers.
Are you.. young by chance? Because I can't imagine an actual adult saying this. No offense intended but.. what?
Generally speaking anyone under 18(give or take) is going to be living with parents/guardians, doesn't have to earn any money or pay for anything, doesn't have any responsibilities or duties that will truly affect anyone meaningfully if they fail to do them.
If a 15yo kid decides to stay in their room playing video games with their phone off for a month, living on mountain dew and doritos, what are the real world consequences for that? Besides loss of opportunity/wasted time, probably nothing of major consequence.
If a 30yo adult decides to stay in their room playing video games with their phone off for a month? They'll probably be jobless/have no income, they'll probably have been served an eviction notice and be homeless, and because they did all of this with no warning, their reputation as a tenant and employee is tarnished and they'll struggle to get another job or home to live in. Their car might get repod if its on finance. Their kids, or any dependants they have(something kids generally don't have) will also end up homeless and starving. Thats called 'responsibility'. You are responsible to others.
That responsibility is the difference. People rely on you, you rely on you. As an adult, you'll often be in a situation(daily) where one wrong move, one wrong sentence out your mouth, one day of 'I can't be arsed' can end your life as you know it. A kid relies on their parents/guardians and can be a total arse, say what they want, do what they want(basically) and still get the grace and lenience of having no responsibilities for any of that to effect.
Obviously all of this is generalizing and whatever, but you get the idea. For the most part, young peoples 'responsibilities' are more like optional extras to create a better human. Most responsibilities for adults have real consequence, greatly effecting the lives of themselves and others around them should they not meet them.
There is a lot I could say on this, but another aspect is social life. As a young person, its forgiving. You can kind of just bounce to new circles, make new friends, join new sports teams, go to different schools or whatever at the extreme ends. As an adult, you are often a lot more.. reliant? On social connections. You have to learn to have patience, forgiveness - throwing a tantrum and starting again isn't really an option like it is when you are young. You find that friends and your social network goes from 'fun' and just talking shit to actually functioning as an extension of your life and capability, your access and ability as a human navigating this world. The whole 'having good connections' thing is real - and can easily be thrown away. It takes a lot more work to build in adulthood. Young people don't have that - social responsibility. Still in the respawn phase.