A lot of the "stupid" rules come down from the lawyers. It's all about liability and avoiding situations where either the customer or the installer have grounds for a suit. The cones probably came from the insurance company, probably as a condition for coverage, especially when the insured is a major corporation as people LOVE to sue large companies.
Such "stupid" rules are common with very large corporations, especially when they have to enter a private residence, lots of liability issues, and large corporations are the ones MOST sued by shady "customers" after a visit because the large corporations have deep pockets. Small local businesses visiting your property for services don't get the lawsuits nearly as often because the slime know those little businesses will probably go out of business BECAUSE of the suit, hence, they never get the money/settlement.
Ironically, these "stupid" rules often protect YOU, the installer, especially as an employee of a major corporation. One could claim you required the "pie" or coke or goodies or you wouldn't preform the work and the customer demands to be compensated in some form or they threaten to go to the AG. You don't see this often if you work for a local plumber, etc., but it DOES happen with the big corporations because they have the deep pockets.
Having a clear policy ("stupid" rule) forbidding the acceptance of such goodies HELPS to protect the company from allegations of goodies in exchange for whatever by the installers. And if the company does NOT enforce this, it weakens their legal standing when trouble should arise.