Just a thougt, but the panel inside may not be a sub panel. I have seen main disconnects at the meter where the ground and nuetral were not bonded at the shut off, but they were bonded inside the main distribution panel. If that is the case, then the inside panel is not a sub and the ground and neutral would be bonded inside. Sometime you have to remove the dead front at the disconnect to see what is happeneing.
So if the neutral is not bonded to ground at service “main” disconnect and there is only a 3 wire feed, 2 hots and 1 neutral, as with this panel, with neutral connected to ground bus, where is the path to earth?
Also when the service wire from the meter connects to the disconnects, the disconnects are now considered the “main service”. All grounding must be bonded together with the neutrals at this point. Any service panels after this point, whether it’s the main service or not, is now considered a “sub-panel” and both the ground wires and neutral wires must be isolated from each other.
There is “service” equipment, and there is “other” equipment. The service-disconnect is located in the service equipment. At that point, there must be a connection to earth, which must be bonded to the service neutral. Refer to NEC 250.24(A) & 250.24(A)(1)
Any panels/equipment on the load-side of the service equipment must have neutrals isolated from the grounding conductors (some exceptions do apply) - Refer to NEC 250.24(A)(5)