For those of us who were around 20+ years ago, the big FT disparity was a way of life with the good Eustachy teams...except it was ISU shooting all the FTs.
There's the way it should be ideally, and the way it plays out in reality. By rule, certain things, like displacing a guy should always be a foul. But in reality, as several others have pointed out, the fouls don't get called unless the offensive player is being aggressive and forcing action. I don't know why, but that's the way it is, and it has been this way for years.
ISU's offense is struggling with this right now, coaches and players alike. They are just too passive on offense when they are facing aggressive defenses, like we seem to see night in and night out in the Big 12. Until ISU gets it figured out, I think these ugly foul and FT numbers are going to continue. ISU has to change, because the officiating isn't.