Turret damage & onhits

Can we get some consistency please? Why do some champions not get their bonus to turrets, while some do? And then there is the doge. Why is it ok for him to walk up to a turret and take off 1/3 or more of its health in one shot while building tank, but it isn't ok for other champions to use their on hits on turrets that do FAR less damage? It isn't a magic damage vs physical either because turrets can and do take magic damage from some abilities. Would just be nice to have some consistency.