Its licence is *free* totally. So that became default font of Ubuntu
18.04 LTS for CJK users. Also that is used most Google products such as
Android, Chrome OS, as far as i know.
are you sure it's more free than fonts-wqy-* or fonts-arphic-*? all three are in main of debian.
i don't like google's free software. it only allows users to install android sdk online, thus forcing developers using latest api. it doesn't release sdk in a file or old sdk.