Right. That's an alternative, smuggle your satellite internet equipment into a country where it is prohibited. Could be risky during the smuggling. Also very likely easy to detect since it's not exactly a LPI (low probability of intercept) signal.

Are those phone companies breaking the law when they let the call on to their network?

Beats me - but I do bet that these companies don't have any business presence in Afghanistan. And despite the Taliban being involved, which most countries in the world (and the UN) don't like, it hasn't been stopped. Which gives you an idea of how difficult it would be to stop ordinary people from using such a service.

Depends which law, and which country.