in my own opinion heres what i think is making these three individuals over power most adcs with the exception of xayah which is who people resort to if the formentioned are banned/picked.
tristana: early game, explosive charge makes it near impossible to win trades against her, later in the game, the range granted by her passive and the resests on rocket jump make it impossible to get to her and with items like GA being much more viable for adcs, its a race against the clock when trying to close a game with tristana on the opposing team. still she is probably the one with the most counterplay on this list.
caitlyn: early game, it is still very possible and to win against her but even if she gets stomped during the laning phase, her insane range (which unlike other champions like kog maw or tristana who have to level their abilities to gain, she gets from level 1) combined with her net, keeps her very well off out harms way. unlike draven or tristana here who have abilities they can rely on. caitlyn doesnt need to use any of her abilities she can stand in the back just simply auto attacking and if head shot crits, the unlucky victim will most likely have to retreat or a running theme ive been having in any game ive had against caitlyn is, they can do terrible during the laning phase but when late game arrives suddenly her damage is unexpectedly high and no one can step in the range of her autos or its gonna be a rapid death and once they are able to buy GA the game is basically over.
draven: to keep it short and sweet. what i feel the problem is with this one is his q and his w. his w is a really good steroid and the fact that he can reset it by simply catching an axe has always looked broken to me. also i think his q should get the tumble treatment and it should not be able to crit or it should be changed so crits only do 50% or maybe even 30% extra damage. draven is the harder one to play on this list but he is still very overpowered in the hands of not so experienced players. he doesnt have the range problem that the other two do but with the one enahcned auto of rapid fire cannon and a statik shiv proc with his q and a crit to top it off is more than enough to make anyone with less than two armor items retreat aka everyone.
right now there is no room to play other adcs apart from these 4 without risking losing the game if the enemy gets their hands on them first and it really takes the fun out of a game.
also as a side note, people are resorting to playing ahri as an adc because of how shit her current state is among mages. who ever is running the balance team needs to get back on their meds please