There should be difference between releasing something for free like Open Source. And then providing real product or service for less than it costs to produce without any alternative income streams.

How would you even define that? Aren't you asking for other people's market dumping to be illegal, but not the type you like?

And what if android charged a penny a year?

The difference is that predatory pricing includes an expectation of future profits from that product. So it makes sense to exclude perpetual free licenses like open source from the definition.

Presumably Google benefits financially from the Android ecosystem. Play store if nothing else.

You can imagine a different world where many mobile OS providers exist, charge you for the system, then comes out Google with free Android, kills the competition and then milks monopoly pricing.

Not presumably. Around the release of android, google was quoting estimated earnings in the billions of dollars from a free and open source Android, purely from capturing mobile ad views/clicks.