True, and I actually considered possibilities like this. But it would be pretty difficult/expensive/time-consuming for people to come to the US, go to law school, study for and pass the bar, and then go back to a low-cost-of-living place to practice law.

In most states, you have to go to an accredited law school in order to even sit for the bar, and all of such law schools are located in the US (and charge commensurately-priced tuition). I believe there are ways around this in medicine because you can go to medical school elsewhere and then sit for boards in the US. Even if you have a foreign law degree, you still have to get a 1-year LLM ($60k) in order to sit for the bar.