You're missing one of the principal actors here. It's not GM or Toyota selling you a car, it's a dealership. The dealership is only viable if they average $2-4k per sale. That margin simply doesn't exist on a $10k car, so they don't even want to offer it except to get you in the door.
Manufacturers in turn (except Tesla) have no one to sell these vehicles, and would have to take a risk that they could make up the lost margin on volume. They don't have the cultures to do that either.
I would be thrilled to pay 12-14k for a cheap electric car with moderate range, rather than 50-100k for an expensive one with 50-100% more range and all the bells and whistles.
Existing contracts aren't structured as a lump sum they can just tack on some margin for and dealers don't fully control their margins. There's half a dozen "incentives" that are given as percentages of sale price plus whatever additional fees they can throw on that need to equal that margin. It's not that these are impossible problems, but they require coordinated action in an industry that's full of mutually hostile parties.
Manufacturers in turn (except Tesla) have no one to sell these vehicles, and would have to take a risk that they could make up the lost margin on volume. They don't have the cultures to do that either.