Hi Steven,
Those are NOT Zinsco panels, they’re labeled Nova which is /was a branch of Westinghouse. I’m not sure where you got the 200 amp and 125 amp ratings from and expect those came from a label on the enclosures, which shows the approval limits of the equipment but does not speak to the max amperage the system is wired for… you’d need to look at the feeder cable and confirm correct breaker size from there. So its quite common to see a 100 amp breaker within an enclosure rated much higher. Not an issue.
As far as why is there a breaker installed within the meterbase… You’re correct in that its quite unusual for this area, as main breakers are typically not located in the meter but installed at the distribution panel inside the home. Main breakers installed within the meterbase is something that I most often see when travelling in the US.
Without knowing more about this place, or if the panel you show is fed from that 100 amp main below the meter, but my suspicion is that Nova panel is likely fed from 100 amps (meter on left) as it looks too small for 200 amps and without seeing inside the main breaker compartment, we’re running blind as far as wire or breaker size. Did you note the main breaker size of that Nova panel?
The 100 amp breaker under the meter likely feeds another panel, perhaps in a detached workshop or some other building (or suite). The story is not complete and you’re probably missing something. That sub-panel is clearly for 240 volt loads only, and appears to be fed from the top-left breaker in the larger Nova panel. It is puzzling as to why the installer cut the neutral off, which just limits their future use to non 120 volt circuits.