Your conspiracy theory may have legs but not for the reason you think. I have seen pro shop operators lay balls out meticulously for their buddies making sure to set them up to roll best under the conditions, while at the same time give thei or non-buddy customers very generic layouts without taking the time to watch them bowl.
Ideally, your driller should set the ball up without a weight hole and leave the hole as an option to tweak reaction. This all starts with order a ball with the right specs for you so that it can be set up without a hole being required under USBC Rules.
Surface has more impact on ball reaction than the weight hole.