I'm guessing you hear a lot more about the failures/impending failures in LBO financing than you do the successes/non-defaults. You could calculate the implied probability of default from the POV of the lender by comparing the financing terms to "assumed risk free" treasuries, and then compare that with the historical data to see how accurate they are at pricing that risk. If you'd rather not do that work, I'm sure there's plenty of papers in the academic literature examining that exact question.