Frankly, and I agree with you,any safety critical item should be checked. How you service them is a different matter
Are you suggesting ATC is a safety critical item? If so I disagree.
It's not a safety critical system as its not statutory requirement for a trailer. It's only an option for new caravans.
If the driver has carried out their responsibilities correctly and loaded both the tow vehicle and the trailer and drives using good sence, the ATC should not be necessary at all.
If a driver finds they are reliant on the ATC to maintain control of an outfit, then there is either something wrong with the loading of the outfit, or the drivers habits. Consider if the outfit is so inherently unstable, if the ATC failed to function the results would be sad, and the authorities would have every right to declare the outfit to have been dangerous.
ATC should only be considered as an assistance device to help capture an extreme not normal situations, It should not be a regular intervention to make an unstable outfit drivable.