Presently the available build minutes in organisations are only available to BB/GH admins.
However, it is often team members who bring in a CI solution. My recent experience has been to spin up some CI solutions on the free tier, in the hope that the reliability improvements brought in by effective CI encourage a business case to be made around CircleCI.
Part of this initial free tier experience is keeping an eye on build minutes, so that the team do not run out mid-month. I don't think it is secret information and there would be no reason to withhold it from non-admins.
CCI-I-881