Hi Bill,
Of the three APIs you mention, only the Reverse Geocoder is Billable. Check out the API table at https://free.blessedness.top/en-us/azure/azure-maps/understanding-azure-maps-transactions to understand the various classes of billable transactions. So for Tiles, see "Render" and it has a note "Yes, the is billable except Get Copyright API, Get Attribution API and Terra maps (MapTile.GetTerraTile and layer=terra) which are nonbillable." The calls you mention are Attribution calls and therefore are non-billable. Reverse Geocoder is a "Search" API so it is explained in that section of the table.
Sincerely,
IoTGirl