Bucking the trend I am going to go out on a limb and say that most, if not all, of the Spectra IV/III domes John shows do not have ptz drives inside, instead I believe that they are fixed domes and/or fixed box style cameras mounted inside of the oversized domes.
My conjecture rests upon four pillars of supporting evidence:
1. Its technically feasible and relatively simple to implement using the dd5-fm adapter:
2. The mail facility design guide (2012), security section, instructs for all sizes of retail post offices explicitly calls out only one fixed camera for each lane pointed at the customer. (Additionally there may be a requirement in certain facilities for an additional OIG (Internal Investigative) camera to be pointed at the register, although this is technically a different system than 'security system'.)
3. John's argument about needless capabilities and Ari's about needless expenditures show that it would be quite a blunder if they really are PTZ's
4. Some of the pictures look like a slanting box camera (to me), in particular the dome in the third window from the right. Also from the pictures on the web it seems like there is too much 'air' in the bottom of the bubble...
As for why? Nothing that stands out but the spec says that sometimes two fixed cameras are to be used so maybe one looking out and one down? Or maybe the box cameras were already purchased and installed but were rather indimidating pointing obviously at the customer so they retrofitted surface mounted domes to keep the cameras and the fov.
John, can you share the branch name, is it the one for IPVM's zip?