I think that when you age you become more respectful. The reason I think of this is because when growing up, you become more mature and you start to know how you need to treat other people. For example, a child (let's say.. middle school age) wouldn't care to be that respectful (though they still might be respectful). But as they age, they get used to being respectful to elders and young ones as well because they might have been in situations that taught them to be more respectful, like being with your boss.
Thank you :)