I haven't used my F100 in a year so i dragged it out to test. I usually use CSM 4 set to disabled so I need to push the AF-ON button to engage the AF. But I just turned it off to test and my F100 is behaving how I think you want it to work when in Single mode. In Continuous mode it seems be doing what yours is. Both 9 and 10 are set to 0 on my camera. Since all your cameras do it I assume it has to be a setting.
Based on the way you are shooting it sounds like you may want to also switch to only engaging the AF with the AF-ON button. Once I did, it cut down most of my frustration with AF. I have my DLSR setup this way too.