maybe the all lightweight 1/10 touring cars can't drift 2wd because they have too small of a moment. any outside force will upset them and spin them out.

1/5 on the otherhand is a lot more slowed down in reaction than 1/10. 1/5 would be way easier to drift 2wd and you can use normal rubber tires as well. don't go changing a huge amount of things though to try and get it to drift. a softer suspension will slow down the reactions and you will be able to hold a drift with the least amount of input. get the hardest compound tires you can so a) they last a while, and b) they will slip easier. try practicing by driving around you in a circle and watching the car as it is about to slip when you give it more throttle. this will be the point your car breaks loose and you can initiate the drift.

with 2wd though you willl need to be countersteering so slow down your servo's reaction time to make things easier.