TariffEvaluator computes start-of-game inertia adjustment separately for every customer

[jecollins]

This is not a bug really, but rather an important bit of code that's in the wrong place. Inertia starts at zero and decays to the configured value over the first few eval cycles. But it's currently done per-evaluator (around TariffEvaluator line 360), which means that if customers do not all evaluate tariffs at the same times, their inertia values will differ. This should probably be done in the CustomerModelService or possibly TariffMarket instead.