I noticed that. Maybe they left that off as well, so that modelers can add their own? I'd just as soon have a date, even if all of the cars have the same date. I think only Bryan matches the dates to individual photos.
Just taking the ACI label off wouldn't mean the rest of the data had to be changed, just weather the car a little more, maybe masking the label location to show where it was removed.
For modelers in the 90s or later it would also be common to have the data itself updated, as most of these cars would have been reweighed at least once.
Off topic, but I saw a leasing company covered hopper in a NS train the other day, nice and clean, with an ACI label. I didn't get the reporting marks, because it was dark, with just my headlights, and the marks were past before the label came into view, so I didn't pay attention to them. I wonder how many cars are still out there with their labels intact?