I’ve said this before and I’ll say it again. Probably several times. The problem with one state having different environmental regulations than a neighboring state would be just fine if the impact of those environment regulations (or lack thereof) only affected that state. And if the people of one state have no problem with living in a cesspool of their own making, so be it.
However, rivers and air currents have no respect for state boundaries. The toxic waste you throw into the river in your state will travel to another state and poison their water supply and possibly even their farmland. The poisons you belch from your smokestacks in your state will pollute the air in the state next door. The refuse you dump into the ocean off your coastline will wash up on the coastline of another state and endanger their wildlife and seafood industry. And if in your state you choose not to do anything to mitigate man-made climate change, that affects everyone on the entire planet.
Of course, if your state is being negatively affected by a lack of environmental protection in a neighboring state, you can try to sue that state for the damages your state is incurring from their actions. Which means this situation is going to be a bonanza for lawyers.
And maybe that’s what Republicans are aiming for.