> Don't even need an entertainment cluster, give me a place to put a tablet or a phone and just have a bluetooth speaker.

Illegal - backup camera is required. Speakers probably too for alerts. Also you are super naive if you think that's where actual cost is.

Most of the cost is in development and prototyping that the company has to make up for, followed by battery as those have a set $/kwh price.

This is why the rest of the car has to be an already proven platform that is cheap to make.