Yeah, I don’t think anyone was saying bald or sanded down tires would be good. If the tires were supposed to be groved but no longer are, those tires are WAY beyond their expected life and need to be changed. The rubber compounds are different than actual slicks and bald tires will never provide adequate traction even with the increased contact patch. Slick tires are completely different.
It’s also a pretty standard margin for most retail stores as well. 30-40% at that scale isn’t surprising at all.