I think there may be a glitch for this reason - if we accept that the highest score for any single target is 100,000, then figure to max the gun out you have to hit those targets seven or eight times, if not more. And there are only four of them that I'm aware of.
I can see one of the youngsters hitting these by accident once or twice. Maybe three times, if we stretch it. Remember, most of these are not targets that your gun would tend to be pointed at just by random chance.
So I think the chances of one of the kiddos who's just enjoying pointing his gun and pulling the trigger and taking in the sights and sounds, somehow nailing a hard-to-hit target seven times by pure random chance is really small.
If you're talking about racking up points from the 40k or 50k targets, then it takes even more lucky shots, although many of those targets are admittedly much easier to see and hit.
Hence, I suspect there's something more going on.
And I have no problem with that - if there's a CM in the back room who decides to occasionally give a bucket of points to a young kid by hitting the "special" switch, that's just great.