This may be possible for a theater hosting a unique event, but never for a music festival, where you have like 30-50 different artists/bands on one night. There you have people responsible for each aspect. Of course you have a stage manager responsible for the overall operation of each stage, but there is no way that a guy can make sure that everything is ok in all details for all artists (the riders sheets can sometime several pages of different requests, like that hotel room must contains this kind of pillow etc.). As you say you have to delegate, and if one of the guys of the backstage team forget to sort the M&Ms, it will be a problem for the guy in charge of the backstage, but that's it. Like in any large organization, you cannot imply that because the customer support guy messed up that all the engineering team is bad. So here, if they wanted to make sure that technical guideline where followed it would be better to put something like: please mark all this kind of cable with pink and yellow tape.