Law is not a static entity, it's morphing and evolving to suit our ideals today. Learning wasn't an issue until it is.
We could very well distinguish between machine learning and human learning although they're no different from each other in principle.
And although, we can't say that ML is plagiarism, at scale it breaches our other moral principles like privacy and individual identity.
Let's say in 10 years from now Google'll train ML on (close to) all the data available in the world, be it text, visual or audio. Would they be able to prompt this AI: "You are George Wilkinson from Colorado ** st. 23". How close will it be from real George on whose data it was trained on?
We can't tune our human learning to this level of precision, but it is only a matter of time for the machine.