Good question, I don't know, but it feels as if their bug bounty service is something that contributes to the level of trust in the apps listed in the play store for which they charge a premium.

Less trust; less money on the line on which to base that trust equates, for me, to a reduced premium for a listing.

Because you used to give a certain % to Google for their service that includes the Security Reward Program. But now that they are shutting it down you get less for the amount you pay for the service.