It isn't a set of abstract logical propositions that are strictly compositional and based on a pre-issued set of tokens with inflexible semantic properties.
It's used by humans. They make assumptions. They use context. They expect inferences to be made. They have a whole set of constraints, most culturally conditioned, that they expect to be followed. And they're free to change the meanings, as a group. Once the avalance has started the pebbles don't get a vote. You're a pebble trying to cast a vote. Sorry.
"Listen" means a bunch of things. It's different from "hear" in that "listen" presupposes some sort of intent and goal. I can hear music or I can listen to music. One's passive. The other shows some sort of engagement.
"Are you listening to me?" isn't the same as "Do you hear me?" One asks for ability; the other is asking about engagement.
If you're talking to somebody with less authority than you and they hear what you're telling them to do, the only reason that they're not doing what you're saying is that they're not paying attention, they're not engaged. To hear and be engaged is to obey when you're told to do something.
There's no change in there. That's been the case since before I was born. I'm in my mid-50s. You can find instances of that going back before 1900. It's just pragmatic inferencing. You may not draw the inferences, you may not like the inferences, but a lot of people draw them and many people expect you to draw them as well.
However, it's been used to many times for so many decades to ask about why somebody's not obeying that it is quite probably, to be honest, shifting meanings. Just like "starve" no longer means to "die" and "control" no longer means just "to monitor or observe", so "listen" now means to "hear attentively" and in a secondary sense means "listen and do as told." Kids have applied the abductive logic that drives language change and have assumed, with sufficient evidence, that one of the word's meaning is "to obey." They've botched the inferencing.
So kids now say, "But you're not listening," forgetting as teens have done for the last 60 years that they have no authority that would entail their parents' (or others') obedience.
"Understand" is the same. If you wield authority then the only reason that a subordinate wouldn't carry out your orders--apart from not paying attention--is not understanding. This, of course, was an inference lost by the '70s when everything was understanding and feeling and logic/reason were down played by all "right thinking" folk.
People are masters of their language until they get stuck on a point. Then they become primarily messers.
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