"There's probably some added legal hassle and maybe even accounting-related hassle, but it doesn't seem significant (arguably even less in some situation, since people from other countries can work as contractors rather than employees)."
As programmers we'd like the simplest possible implementation of hiring: I would like to post a job offer for role x at salary y regardless of hiring location.
The reality of implementing that as a business in a compliant manner - involving international payment methods, tax reporting implications across multiple jurisdictions, legal implications, etc do not strike me as trivial -- if you're a small company they're time-consuming and require expensive consulting, and if you're a large company it may be difficult to get your internal tools and processes to align with them.
I'd love to be proven wrong, and would like these systems to be simpler and fairer. They certainly shouldn't be torn down until the positive reasons for their existence are understood and handled.
I feel like many common narratives around 'programmers can work from anywhere' come from a naive point of view and rarely include details about how to compliantly achieve those results, from either the business or individual's point of view.