But it offers no data to support the general idea that this is the case (that denials are through the roof, even if TN is a higher rate than the national level,

But it offers no data to support the general idea that this is the case (that denials are through the roof, even if TN is a higher rate than the national level, it is marginal. Also it leaves out the median which would be more interesting, since a few states could greatly bring down the average.) The approvals are reviewed because denials can be appealed. It's a safe guard against fraud. I'm not saying there aren't perverse incentives, but "doctors earn big money approving disability claims" has less of a moral outcry from the reverse.