Ming from Agents of Speech explains why young children seem not to listen: they're actually guessing what you mean from context, gestures, and routines rather than processing your words. A child told to throw away dirty paper might understand only the situation, not the language. They look disobedient when they're really just working with incomplete information.
You need to understand. Children are people who don't have a lot of language. They use the context to guess what you mean. For instance, just like a foreigner in a foreign country, when a local speaks in their local language, the foreigner doesn't understand. They will use a lot of contexts, their hand gestures, their eyes, right? The general what's happening around to guess what the person wants from them. Same as children, they use it more often than you think. For instance, if you give a scrambled piece of paper that's dirty, say, put it in the bin, what else can they do other than that, right? Go throw it, right? You would know what it means because the context is helping you. When you see kids, they know when the food is coming out and go sit down for dinner. It's easy to guess, right? So you need to know if your child is using context to guess what you mean. Because it's more efficient that way for them to think instead of listening to the whole thing. They just need a guess, right? That's why they're not trained to listen.
