But it's illegal... in most countries hawala is illegal, and prosecuted under various money laundering laws.
That's most definitely not true. I know a hawala company that has offices in several western nations like the U.K. and Australia and they're not operating illegally to my knowledge. They essentially work like Western Union and simply operate in markets Western Union does not serve.
Might still be illegal in Uganda. Enforcement of bans or regulation can be erratic of course.
(Hawala is apparently completely illegal in India and Pakistan).