Legitimate question: How can US measures stop climate change if many other countries are planning to construct and operate hundreds of coal plants for electric generation?
If the US ignored it and does not take action, other countries are less likely to take action, because the U.S. is generally a leader on these things.
It's kind of like asking "If the US stops pooping in the pool, what's to stop another kid from pooping in the pool?" Well those other kids are a hell of a lot more likely to poop in the pool if they see an international leader doing it.
Also, by leading the way and showing how decerbonization is not only cheaper, but also healthier, other countries will be more likely to try to save money similarly.
Most places that are installing coal these days are doing it because of local corruption. It's a lot easier to grift off a huge project than it is off of small distributed energy. Seeing that the US is moving away from coal will mean that corrupt local officials will have less excuse to pick outdated technology that lets them get bribed.
This is a separate issue from federal action. We take all sorts of actions with vast political and economic action that don't save money, to reduce pollution.
But by leading the way, we will encourage other countries to not build coal plants, which was the "legitimate" question that was asked.
Higher standards in California mean companies default to that standard nation wide because it's easier to have a single product and avoid supply chain issues.
Same reason most all orange juice is Kosher. A small but large enough hard preference controls the market because the rest dont care enough.
Hopefully red states won't put an mpg cap out of spite
Also California has it's own specific blend of gasoline and that hasn't been adopted nationwide at all. It's only used in California.
Texas produces around five times as much wind energy as California, and for half the price of California's wind energy.
Unless you can identify a certain thing in California that caused Texas to increase it's wind power I think your argument is pretty vacuous.
I ran the numbers a few years ago to see what personal actions I could take. (Even though climate change is a collective action problem, not a personal action problem.) In the US, stopping buying so much stuff isn't much of a climate action, at least not nearly as much as switching off driving a gas car, changing your natural gas water heater to electric, ir changing a natural gas furnace to a heat pump.
In practice I'm not sure how anyone is going to make a dent without switching to nuclear power.
If you want to be really self-serving and hypocritical about this sort of thing, you can even skip out on doing the first part, and jump straight to the second.