If you are near her alone you're wrong. If she's attacking you and you aren't alone, it should be because she's shooting the wrong person (not the carry) and going to lose the fight because of it. If you're just stepping in her traps frequently, you need to pay better attention.
If you can't get into position to harass her without losing more than you deal, don't try. Harass the Support instead, or don't go in at all. Zyra and Karma both have a ton of range on their harass and her range shouldn't be that big of an issue. Whatever you play, harass when she's going for CS (like you would any ADC), stay behind minions so she can't net you, and don't fight when her Headshot is up naturally (she'll always want to hit you with it if she's close). Janna and Soraka can play so far away from her they don't interact. Nami and Sona only need to get close for half a second then leave, healing up the trade.
If your ADC can't farm, it's either because you're providing no pressure, or they are failing to avoid her strengths as described above. You can't make your ADC not eat the cupcakes, not trade when her Headshot is up, or not dodge skillshots. If that is what you think your job is you should play Braum.