Really? I'm not there quite as frequently (I usually get frustrated at that store because it won't have what I needed and I end up having to go to Elston), but I have never once seen an attendant there. The notes on spothero about validated parking for HD/Guitar Center are odd because I've never once seen the gates in use, they've always been up.
Literally 2-3 times since it opened, what?, 4 or 5 years ago, including once in the 4 months since we bought the new place (during which time we've probably been there once a week, on average). I really have no idea how or why they decide to staff it on the extraordinarily rare times it is staffed. It's very odd. Either staff it, or don't staff it.
(BTW, I agree with your frustration with that store! Even the stupid parking lot makes me want to tear my hair out. However, it has gotten a deeper selection of stuff since they significantly expanded the second floor, but fix the darn escalator already! I know there's the internal elevator, but it feels ridiculous to use that if you don't have a cart.)