Ming from Agents of Speech explains why speech-delayed children tantrum: confusion makes them less likely to engage. Sensory overload, not getting what they want, and not seeing an end to interactions all trigger meltdowns. You can't force communication, only make it clearer and more worth their effort.
You cannot force someone to communicate. You can only create an environment that is obligatory. It's more have benefit for the child or the person to communicate with you so that they get what they want or that they get more of what you're offering. What that means is not always rewards, it's not always toys or food or whatever. We need to get to the reason why children don't interact with you most of the time. It's because they are confused. So the number one reason for confusion is tantrums. And there are loads of different types of tantrums. There's like sensory overload, which is kind of a confusion. Different people are sensitive to different types of sensory. Right? Other than that, there are a few. Like children don't get what they want goes into a tantrum. They try to escape because they can't see an end to what you're trying to offer to them, so they try to run away. They protest as well, because at the same time it's a confusion because they also, they cannot see when it's going to end, why is it beneficial to them. And therefore they're protesting to get out of a situation or get what they want.
