Thanks for your feedback :) You have to send quite a few json messages to fill up 1GB. We think overall thin provides a lot of value and saves a lot of developer time (atleast for businesses), so we price it as that.
Bandwidth is frequently used in the context of file storage which can get expensive really fast even with a few users.
This doesn't translate well on the data side where most json responses will likely be lower than a few kb.
It's extremely unintuitive which is why I think most Paas providers use request and inflate the number (10 million requests sounds a lot in comparison).