Every time a friend of mine bought a phone in a country like China or Korea, the camera app had built-in filters to smooth the face and prettify the eyes. Often times these were also the default setting. So I think we are already at that stage in some parts of the world
Samsung did this with the Note 3, and I suspect other flagships around this time.
The rear-facing camera would default to their 'Auto' mode, switch to the front-facing and you have to switch out of something like 'Beauty' mode with tons of post-processing for selfies.
Selfies are inherently at a disadvantage, because shots are very close range with a wide angle lens exaggerate depth. Portrait photography is usually done with longer lenses, which you can't fake computationally so easily. So I think some of the selfie postprocessing is trying to make up for that.
Here's a conspiracy theory: what if some/most phones do this to some level noticeable only to the subconscious without any user knowledge of it happening? Maybe as some sort of marketing ploy to increase positive word of mouth.
"Hey $FRIEND, this new phone is great! I can't believe how good it makes me look. You can really see my eyes. Check it out!"
