EV batteries undercut stationary-optimized batteries in $/kWh because EVs are lucrative enough to drive the research that much harder. Without the EV industry as the incubator for competing battery tech, stationary storage would still cost what it did in 2010.

Cool but that's beside the point. I don't care how lucrative a market is for some aristocrat arseholes. I want what's best for society as a whole, not the pockets of aforementioned aristocrat arseholes.

If we put all the money and effort that went into researching BEV batteries into researching and developing grid-scale batteries instead, I imagine there's a good chance we wouldn't need coal power plants anywhere on earth anymore.

I have absolutely no clue about your example but you can ask the same questions: If the R&D went into relay tech instead of IGBTs, wouldn't you think those would be even less expensive for your use-case?