Our local Lowes used to be darn near useless in terms of customer service. Then Home Depot built a store less than 1/2 mile away. That caused a huge turnaround in attitude at Lowes. I think it's all about competition, and whether or not they need to care. Both stores have pretty good service now.
When I was a teenager, I worked for my dad's construction business, and one of my jobs as the "gopher" (go for this, go for that) was to get materials from the local yards. One place in particular was family run. The old man at that business was mean as heck, and would great all customers with a scowl as if they were causing him a problem. Talk about intimidating! The sons were nicer, but not super outgoing. We probably gave them over $50-60K in business per year, and this was back in the 80s. My dad said they were the only lumber yard in the area, and they didn't have to be nice. He did get into it with the old man one time, when they sold us a cube of lumber that was almost all punky, and wouldn't take it back. Boy, talk about a battle! From then on, we ordered cubes straight from Georgia Pacific, and only went down to that yard for small purchases.