If you try to close the gap as an adc on a mage without backup, you will regret it. You would need to heavily outplay that mage to be able to kill him. Minions usually only really matter early game in laning. I don't play adc mid lane vs mages so I can't really answer for that, but for mid-late game, minions don't mean anything other than for sieging. I usually don't think about outplaying someone just by the usage of minions in most cases when I walk up to aa. I usually try to predict the skill shot and then dodge up or down, depending on how I predict.
Wave clearing as most assassins is suicidal if the enemy team is near. If the enemy fizz presses e to clear wave, he can get immediately collapsed on the moment his pole ends, in which he would either have to burn flash, or die. It's the same thing for most assassins. The most you can do for safe wave clear is zed shadow + e and q, or Diana Q. There's other assassins I probably missed that can do that but it generally won't clear the whole wave.
If you only take out what both classes do that are similar, then you can make one sound better than the other. However, mages do a lot more things than CC so you can't really look at 2 individual similar things and forget the rest. Tanks are melee (except gnar) and generally do not do as much damage. You need to step into the minion line to wave clear, usually. This leads to a similar issue like assassins where it can get risky. In most scenarios, since you are a tank, it won't matter but you could get caught from it and end up dying.
Two aa on adc won't do as much damage as a mage. However, there's a ton of mages and a ton of adcs so it's hard to tell in a vacuum, what 2 classes will do more dmg in that time period. If you compare mages like orianna to an adc like trist with 2 aa, orianna's full combo will do more damage than the tristana's 2 aa. If Oriana only used her q and w, I think the damage will be about even, maybe slightly in the favor of orianna but it won't be a huge difference. If you compare tristana and ahri, then I think tristana's 2 aa dmg will out damage ahri's e and q combo, maybe her w as well. However, ahri's full combo I believe will out damage tristana's 2 aa. You also need to remember that ahri's charm is a pretty long cc ability, so that will also go into how effective the champion is compared to another. The only burst I will say is dumb is rapidfire/shiv combo on adcs. That combo has made the crit adcs really dumb in their first shot burst dmg for a while.
Mages can have their skill shots dodged, but the adc can also be out ranged by the mage. If I am playing Caitlyn, who has 650 range, then my range effectiveness is 650. However, xerath, who has around 900-1200 range effectiveness (idk the exact range of abilities but only the difference really matters), the xerath will heavily out range the Caitlyn. Caitlyn will need to dodge every ability to be able to close the gap on xerath and only if he decides to stay in 1 spot. Xerath has a much bigger control area than Caitlyn and so he has more room to play around with. The only thing that changes the range effectiveness with with rapidfire cannon but xerath still out ranges it. Also, xerath has more damage in his 3 combo than 2 auto attacks.
Also, ADC is a late game class while mages are better early game and maybe mid game as well. Both scales well but ADC is meant to be one of the strongest roles in the late game.