I'm pretty sure that years ago (perhaps as far back as when they were rotating the three divisions as well) they were rotating field events. At some point, these rotations stopped and nobody bothered to line them up to match the regional competitions.
The district competition order is set by your district, not Columbus.
Also, Probably due to the State Meet Facility hosting all three divisions instead of just hosting one field event for each gender. At the state meet, they have 3 Shot Puts, Discus', HJ, LJ and PV for each gender AND want to be completed with each division prior to the conclusion of the finals in 4 x 400 so they can announce team results. That is why all the DIII field events are held on the first Day since the DIII 4 x 400 is scheduled at noon.... and all DI field events are on the 2nd day and prior to 3:00 (so they can be done by 7:00 for the conclusion of the DI 4 x 4. DII is divided up with half on each day, but both days are in the a.m. so that kids who may be in track events too, do not have to "check out" for a running event.