I think there's some misinterpretation here. I don't think anyone is saying that black parents or Southern parents are the only places you will find child abuse or spanking. Of course you will find both everywhere. What we are talking about is the location of the "acceptable" line somewhere between an occasional light swat on the bottom and obvious abuse.
I don't believe Barkley is saying that spanking is only done in the South or in black families. He's also not saying that what Deb described is acceptable or only seen in the South or black families. He's talking about spanking methods and the placement of that "acceptable" line. Specifically, he was talking about getting whooped with a switch that might give you welts. He was saying that in the South, that is on the acceptable side of the line. In New York and California, it is on the abuse side of the line (in general, not any one specific family).
To restate, I bet you'd find that whippin' with a switch in this manner is significantly more common and acceptable in families with southern roots than families with California roots.
"Just think of how stupid the average person is, and then realize half of them are even stupider!" -- George Carlin