One reason that I'm sure is a factor in the difference, is that companies are less inclined to bother reporting the "past due" status.
There's another reason that people seem to be ignoring: something that is "past due" will change out of that status, one way or another, after a short time. Something "in collection", not so much. One has to consider why it went into collection in the first place.
Another factor that is rather passed over in OP is that despite a few changes that were made for the better some years ago, they were actually pretty weak changes and credit reporting is still egregiously one-sided today.
Most companies of any size have whole departments that regularly report "past due" debt to collection agencies. But a consumer has many time-consuming and often expensive hoops to jump through to get that back off their record. In many ways it's still guilty-until-proven-innocent.
The fact that over generations people have become used to this travesty of justice just makes it all the more insidious.