Sherwin William's and other like that have a large percentage of their business in contractor customers. Contractors get a pretty good discount from them.
I for one, and many other contractors feel this way too, once your settled in with one particular brand of paint and its charactericts and the different tips for each type of paint, YOU DO NOT WANT TO SWITCH. Brand loyality is very very high amount contractors and when a contractor paints a customers home, the contractor will use their brand and leave some left over for the customers touch up and that paint will also have long residual loyality, because you have to stick with that mixture and brand.
Your particular problem with Ben Moore could have been the cutting in and rolling line. This is something that you have to handle with care. When you do the cut ins, the paint is thicker off the brush and it dries before the roller paint is applied.
So, when you then come back to do the roll on, the brush cut in is dry and the roller may not be as thick and you have shadows. You cure shadows by doing the feathering in after the wall has all dried. But this is common with any paint unless you have a cutter in person and behind him immediately a roller on person so that the roller person will feather over the brush area and eliviate the line completely.
I would not consider buying a paint store and thing you can pull customers over from one to another. Too set in their ways.