I believe the caster/camber measurements with neutral pills depends on the manufacturer. My CRG at neutral is the factory “ideal” setup, and it has a little bit of positive camber when on the stand. Keep in mind that resting on the ground with the driver in it will cause the tires to lean in (negative camber) a little bit. On the ground with me in it the tires are likely standing straight with zero camber, at neutral settings. If your kart has Sniper compatible spindles on it you can leave the lasers on with the kart on the ground and your son in it to find out what the difference is.
What kind of Kart is it? What kind of caster/camber pills? Does it have sniper compatible spindles?