It's hard to see any of this as "trivially fixable." Taxes are inherently political, politics are complicated, changing incentives on this scale are pretty much impossible in our political system.
"Taxes are simple... and they don't have loopholes" is not at all how taxes work in the US. Perhaps your imagined perfect carbon tax is simple, but a simple tax with no loopholes is not likely to happen. Everyone wants a break or exception, and many of the interested parties are powerful.
This is mixing two questions: whether a system can be elegantly designed and do the job without major market distortion, versus the question of whether various actors will stand in the way to prevent it.
You could say the same thing about zoning. Higher density is better for affordability, but faces opposition from landowning existing residents. Does that make it wrong, or not worth pursuing? No, and that particular movement seems to be getting traction despite the political opposition.
I read "trivially fixable" as "there is an elegant solution to this," not that "it is easy to get it politically passed."
As we learned in the 90s with email, an elegant solution that doesn't take human nature into account isn't worth pursuing. There used to be a joke checklist we'd send to each other about this.
> I read "trivially fixable" as "there is an elegant solution to this," not that "it is easy to get it politically passed."
The huge problem with this line of thinking is that it's easy to identify a half-dozen key players standing in the way of your elegant solution and it would be easier to remove them from the situation than change their minds. It's an attractive idea that can become a fixed idea.