It's not hard. They should just upload the ones they used to build the image they distribute. If they don't they are just not worth buying anything from. I wish more developers would care. Are you a known license violator? No responsible disclosure for you, no "workaround in our app to make it work better on your device, fix your shit yourself", etc., etc.

Why would they even bother?

The weird Western altruism embedded in the GPL is completely alien to Chinese culture.