I mean yes, I realize that cost-of-living-wise, $30 in Zimbabwe is the equivalent of about $400 in the U.S. after adjusting for average salary, but either it costs money to provide data or it doesn't,
What you are not thinking about, is that probably a user in Zimbabwe is not using nearly so much data per month as a US user.
MY mother uses Starlink for example (vastly better than any other solution she can get in her rural area), and even she has something like four devices that all use the internet, update frequently, and she has a lot of people she communicates with including video calls.
Now someone in Zimbabwe, they are probably on average not going to have so many devices, probably not doing as many things like video chatting, so I can easily see them using 2x less data than most US users, maybe up to 4x.
Also do you not think there's a likely component of trying to help countries that have generally poorer access to technology by artificially lowering Starlink prices even if they have very little, or no profit margin? A large part of what Starlink does has been humanitarian in nature, like deploying many Starlink devices for free in the wake of natural disasters.