Even if the Chromebooks aren't subsidized, Google Apps for Education is free to use which amounts to some kind of subsidy.
Google Classroom is not free and schools pay per recurring per kid.
Pretty sure they're subsidized. Plenty of products given to educators are subsidized. That in and of itself is not bad or wrong. It's when we put things in the proper context and ask how exactly does Google benefit from this that things take a wrong turn. I don't see how any positive spin for why Google is doing this actually holds up.
CB are not subsidized and schools pay for Google software recurring per kid.