This isn't a conspiracy theory - I worked on projects around that during graduate school, and talked to my colleagues who worked on them. Cost-effectiveness thresholds are a consideration that goes into how widely a vaccine will be rolled out, etc.
That was, for example, why boys were originally not part of the recommendation for the HPV vaccine. It would double to cost, while doing very little to prevent cervical cancer via indirect protection. Once the evidence accumulated that it was associated with other cancers, that stopped being true.
Similar logic applied to older women and men.
