Familiarity is the missing element. You know the layout of a store. You know the people. They carry the brands you like, it is convenient, it is all of those things.
I never took part in a buycotts intentionally--if that was the place I shopped or had the item I needed, I would go there. I do not support boycotts because they are ineffective. The first people that will feel the pinch are the employees who have nothing to do with company policy. Next will be the people who must stop delivering the products to the store that people are not supposed to buy.
I will write letters to management, corporate leaders, local and national newspapers if the cause warrants it.
Please, I ask no one hand me a extreme case where underage children are being held captive at a local store and forced to work 18 hours a day.
Thinks happen in the chain of supply to stores that I may not like, but the boycott has proven to be mostly ineffective.