My assumption has been that they'd attempt to infer by marrying the two pieces of info whether it bit you'd pose a risk. So say you have a fraud charge laid against you some years back and you're currently in heaps of bad debt... It might be a bad idea to let you at my financials database, for instance.

I do think though that some of the more stringent assessment procedures also serve a secondary purpose when it comes to offer time. If you've run the gauntlet to get this offer the person offering you the position has considerable leverage in terms of negotiating a remuneration package. May it's not the main reason they do that stuff but it is a side effect of it.