It may have to do with the individual store itself. I've noticed that the Lowe's in Bellevue, where I used to live, carried a smattering of plumbing products that I needed. When I moved across the way I noticed that the store nearest me carried lots of plumbing, but little electrical. Overall it seems that each store carries what sells in their area rather than a single product line across all stores. I don't know about HD, I only buy Leviton switches and outlets from them - nothing else if I can help it.