There is definitely more of a "community" aspect around gaming, wherein everyone wants to get the midnight release or download the DLC the moment it is ready -- I can see how that creates technical differences in terms of the value console platforms may deliver to a developer.
I would be unkind, though, if I didn't say there does seem to be a rough equivalence. The value provided might be different, but we can clearly see the lines get more blurry with hybrid devices like the Nintendo Switch.
I would assume Epic is targeting Google and Apple because they have much higher gross margins on services (I think 60-70%, which is pretty normal for SaaS, vs around 30% for something like Xbox Live), plus the additional scrutiny mobile phones are under in general. Probably makes the case much easier. The cut does seem pretty hefty when considering most of that money is just going straight into profit margin. Irrespective, I wouldn't be surprised if decisions in the mobile realm find there way as precedent in other, similar cases.