ARC benefit - outsmart streaming blockers on some public WiFi networks

So I’m not sure how this works, but there are some WiFi services that explicitly and successfully block all streaming and file downloads (ie I can confirm that none of Spotify, Qobuz, Tidal work). But ARC manages to circumvent that somehow, making it possible not only to get content from my home network, but to stream from Qobuz / Tidal. However, in the two cases I’m talking about (one a local coffee shop, the other is Amtrak trains), streaming worked as advertised but downloads via ARC were blocked.

Not sure why this would be - how they are blocking in a way that ARC fools the blocking - is it just some sort of proxy, and ARC is too new/small to be noticed yet? If so, hope no one in Amtrak IT reads this and puts the blocker in place - I take Amtrak all the time!