I don't disagree with the spirit of what you're saying. This is a burden for expat US citizens. A few notes and corrections though:
> Moreover, it makes expats ineligible for certain retirement savings in their country of domicile (as the US does not recognize pre-tax deductions for these investments, like those countries do not recognize investments in 401k’s).
This is true but unrelated to taxing worldwide income. Basically, there has to be bilateral/multilateral agreements between countries about how to treat contributions to and distributions from retirement accounts and these are very few and far between.
The US and Canada have such agreements but the US and Australia do not. So Australian superannuation accounts generally can't ever be closed so you have to keep reporting them to the US government every year, whether you're a citizen or not. Even those on work visas have to do this. Worse, it's unclear how gains in such accounts should be treated for US income tax purposes. There are literally no laws and no case law on the subject so everyone just has to guess.
> It also makes it challenging for expats to find banks willing to serve them because elf the added complexity.
So this is also mostly true but again (mostly) unrelated to taxing worldwide income. This is because of FATCA [1]. The US uses access to the US financial system as a wedge to get foreign financial institutions to report accounts of US citizens so being a US citizen imposes a reporting requirement on foreign banks that many don't want to deal with. It's easier not to offer services to US citizens. But again, FATCA reporting requirements aren't really the same thing as taxing worldwide income.
> ... lost taxes to be a mere fraction of the costs of enforcement.
The point here unfortunately isn't really to enforce anything. It's so if the US decides to get you, it's something else they can prosecute you for.
> This makes literally zero sense.
That's not strictly true either. The idea is that US citizenship is so beneficial that it justifies these costs. It's true that a US passport gives you a lot of access to various countries. I believe the US passport is right up there in the top 10 passports. I'd hazard a guess and say the only reason it's not even higher is Middle Eastern countries. Also, the State Department will make some efforts to recover and evacuate US citizens in certain circumstances.
Is this worth the hassle? Probably not but for some it is, I'm sure.
Still, there's definite room for improvement.
[1]: https://www.irs.gov/businesses/corporations/foreign-account-...