Need some insight on Trailer Tandem regulations

Look at any rand McNally atlas under weight & size limits. Than you will know the king pin to rear axle lengths for each state. A good case in point; Il, any trailer over 48' is 42ft 6 in from king pin to rear axle. Per the 2020 atlas.

 

So slightly off topic, but..

I don't quite understand why us 48' & shorter wagons get the kpra exemption.? I mean, yeah I'll take it. But mine still pulls longer, off tracks worse & will do more bridge damage than a 53' box with a 41'or 43' kpra distance.

My 48' step has a 13" kingpin setting, & rear axle is 30" from the ICC.
Can someone explain why 48's are exempt with about a 44'.5" kpra distance..

 

Because the bureaucrats wrote the rules....