The current I-65 widenings are also short sections.
My opinion is that the most increase in traffic flow and safety for the dollar will be based on actual traffic volumes. It would be very hard for INDOT to justify favoring only two highways when there is objective evidence suggesting the needs are higher on other highways.
One factor not mentioned for I-65 south of Indy is that the completion of I-69 should reduce some of the I-65 traffic headed to places like Nashville.
Sure, you can cherry pick data in lots of ways to make your argument. A better determination of need would not be traffic counts over short segments, but average traffic counts over longer stretches. You might wait a mile or two to get by a truck on 69, you can wait 10+ miles on 65.
Luckily, INDOT seems to be taking a more evenhanded approach that at least somewhat corresponds with traffic counts.
Since around 2005, both I-69 and I-70 each had four sections widened and I-64 is getting one section widened in addition to the approximately nine or ten I-65 widening projects. I believe a section of I-70 west of Richmond is also going to get widened.
I rarely drive I-70 so I can't speak to that, but there are absolutely zero sections of I-69 that are only 4 lanes that are as bad as I-65. Traffic volumes may be comparable but I-69 has far, far fewer trucks.
I don't remember where I saw it, but I-65 has significantly higher accident rates than I-70.
So yeah, if I was only familiar with I-65, that is the road I would favor also. But I live closer to I-69 and I-70. I can guarantee both highways carry heavy traffic volumes.
FWIW, the busiest section of I-69 has an AADT of 155K while busiest section of I-65 (other than where it overlaps with I-70 in downtown Indy) has an AADT of 126K. The I-465/I-69 north interchange is the busiest one in the Indianapolis area. So it is not like I-65 is in a league by itself.