I know at least 2 ACU T&E committee members that mark out trials, observe etc and are the clubs that you say are picked on by the ACU.
In this claim driven world getting all the Ts crossed and Is dotted is the only way to avoid huge payouts or negligence charges. Admin costs money unfortunately
A percentage of the money paid to the ACU from running an event is for insurance to cover officials, 3rd parties and even riders. As an official you are covered even when marking out a trial or going to look at a venue for sections. Easy to knock until you are a beneficiary.