They're using a non-disclosed algorithm to calculate an "average" that's not really an average, and holding on to all the money above that, and charging you $3/week for the privilege. If they haven't already constructed the algorithm so that its nearly impossible for them to ever be giving you a "boost" other than from your own deferred wages that they are holding on to, I'd be surprised.
> However, the insurance companies are also great at modeling their customer's risk.
Insurance companies also have to disclose the terms and conditions, including, particularly, the specific events that qualify for a payout and the amount of the payout; Even does not disclose this.
> It is a natural information assymetry and I'm not sure how Even could have a better idea of a customer's future earning then the customer.
Because of the non-disclosed "average" algorithm, there's an additional -- and potentially more significant -- information asymmetry working in the opposite direction of the one you describe.