I don't think this is true. I do specialize in ML and you are probably talking about neural networks ("deep learning"). While they do require a lot of data for most tasks, it's still finite and after a certain size the improvements are not significant anymore (the definition of significant is up to you..). I don't know what Apple is working on, but i think for most of the ML-applications they are interested in, getting the training data is not that hard (like suggestions on the photos-app or autocorrect). It's still apple.
If I remember correctly, sharing analytics info etc. with apple is opt-in? If 1% of the users share the relevant data (or you've got money for annotating data in asia/africa, like tesla), this might enable you to solve most of your problems.
this does not mean that the quality of apples solutions is the same as googles, i just doubt it's the training data. Google is A LOT (not even comparable) more visible in the ML-community and i bet they have better and more researchers.