Seriously? If they move to Singapore why should they ethically be liable for US taxes anyway? It's not like the US provides exemeplary services to non-residents that are superior every other developed country (which all do not tax their non-resident citizens). For instance, they didn't even opt to evacuate most citizens out of Yemen and requested help from India to do so.
So no, I don't support paying taxes for services I don't receive. If I had to make an analogy, it would be like a remote worker being charged for a catered luncheon that he/she clearly can't attend, and when asked about being exempt like every other remote worker, being told that he/she became a remote worker solely to avoid the lunch payment and so should not be exempt.
> Because they actually derive their entire income from work done and assets owned in the USA
How many people does this even apply to, compared to the vast number of US citizens abroad (some of whom are not even aware they are US citizens) who owe US taxes on income from local sources? If you really think this makes sense, then tax it, but that isn't how income tax works today for expats who are taxed on all of their income sources (globally) above the exemption.
> don't even really live in Singapore
There are laws in place to establish residency with a reasonable degree of enforcement.
So no, I don't support paying taxes for services I don't receive. If I had to make an analogy, it would be like a remote worker being charged for a catered luncheon that he/she clearly can't attend, and when asked about being exempt like every other remote worker, being told that he/she became a remote worker solely to avoid the lunch payment and so should not be exempt.