I don't think it is an unreasonable hypothesis that GE renewal could be cheaper than the first time application. There are a lot of things in this world that are cheaper to renew than to initiate. For example, the cost of a renewed passport is lower than the cost of a first-time passport.

In the case of GE, I would think that in the case of a renewal, they would not need to interview me again, and probably either not do a background check, or do a more cursory one, all of which would save the government money, which one would think they might pass on to me. And besides that, the more people who have GE, the less that CBP needs to spend on staffing immigration checkpoints at airports.