For some "a little friction" is enough. For others, not. I keep less-healthy food treats in a cupboard in my garage, because the friction of walking out to get them is enough to reduce my usage to an acceptable level. Even less healthy treats I don't buy, because the friction of going to the grocery store to get them when I'm craving them is enough.

It's an interesting exercise to think about how this could be engineered to increase the friction.