That's a bad example. There are apps where you absolutely not know. It's not even a "subjective issue".
As long as you have either
a) wrapped native widgets with the same look and behavior as native (or a fully skinned app vs a fully skinned native app)
b) response times below some objective, determined by human physiology, threshold
Then it doesn't matter if it's a higher level framework doing some wrapping, you don't know it at all.
That's a bad example. There are apps where you absolutely not know. It's not even a "subjective issue".
As long as you have either
a) wrapped native widgets with the same look and behavior as native (or a fully skinned app vs a fully skinned native app)
b) response times below some objective, determined by human physiology, threshold
Then it doesn't matter if it's a higher level framework doing some wrapping, you don't know it at all.