When I was last involved with Airbus deliveries, Airbus used to invite the customer's delivery team to participate in all the acceptance tests including engine run ups. The aircraft were taxied from the delivery centre to the run up area and back and the customer's ground crew even got to try their hand at taxying which may have something new for many of them. So the question perhaps should be who's hand was on the throttles (and feet on the brakes)?
All the jet aircraft I worked on could be held quite satisfactorily on the park brake. Park brake pressure is usually a lot less than than max. The brake pressure required to prevent stationary disc's from rotating is a lot less than that required to slow rotating disc's down. For instance, I seem to recall the DC8 only applied 700psi with the park brake set pressure whereas max brake pressure was 2,000psi.