For example, Alice gets on the freeway and merges 4 times (after the initial merge) to get to the "fast lane". For ease of explanation, the lanes will be referred to like this:
| HOV | 5 | 4 | 3 | 2 | 1 | Onramp |
Traffic starts slowing down, so she merges from lane 5 to the HOV lane in order to pass a few cars. She's in this lane illegally so she doesn't remain in this lane. After a few passing a few cars, she merges back into lane 5. She repeats this 3 more times before she gets off the freeway.
So, in this limited example, this is the "transaction count" of Alice's lane changes:
Onramp <-> Lane 1 : 2
Lane 1 <-> Lane 2 : 2
Lane 2 <-> Lane 3 : 2
Lane 3 <-> Lane 4 : 2
Lane 4 <-> Lane 5 : 2
Lane 5 <-> HOV : 8
Similarly, lanes 1 and 2 have higher transactions due to people getting on the freeway for a mile or two and exiting shortly thereafter. This may be limited to AZ freeways since the exits tend to be regularly spaced about a mile apart. The other problem is that there are quite a few people who will merge on to lane 1 going 45MPH, which causes many drivers to pass them in Lane 2.
Chronic lane changers seem to use all lanes roughly equally, so their habits mostly cancel out.
Another thing that may be different depending on where you live is that AZ allows entry and exit from the HOV lane at any time. It's not like CA where there are specific entries and exits to the HOV lanes.
Let me know if this still doesn't make sense.