There was (understandably) a lot of negativity around the switch from pay-to-play to buy-to-play with optional sub and while most of that was directed at ZOS some people, both those who intended to keep subscribing and those who didn't, were concerned that one group would discriminate against the other in-game.
So one of the things ZOS promised was that there would be no way for other players to tell subscribers and non-subscribers apart (unless you played with them long enough to notice that one person is levelling up faster than another while doing the exact same things).
(It was also part of promising that the crown store and sub wouldn't be constantly pushed on players, but I think that went out the window when they abused the in-game notification system to spam adverts on screen for everyone who happened to be online at the time.)
It's not completely fool proof, at least on PC. Srendarr shows the buff (although there's an option to turn it off) and I assume other buff tracking mods do too. But that's why there's no title or other marker to show who subs and who doesn't.
PC EU player | She/her/hers | PAWS (Positively Against Wrip-off Stuff) - Say No to Crown Crates!
"Remember in this game we call life that no one said it's fair"
Ah thanks for the informative post Danikat.
I am a new player on the ps4 so didn't know the backstory behind the change over from subscription based to optional.