Re: What about the Oakland station at the stadium?
I believe neither of the 2 Amtrak lines; Zephyr or Starlight utilize this stop. Only Capital Corridor trains.
Why did the Starlight ceased operations at the Richmond CA BART station but not the CZ (Zephyr)?
There was not a problem with the CZ arriving while the station was closed. You answered your own questions above.
"Assuming the info about 14 is true, then the answer about the CZ would be...
*** The Richmond BART station had a multi-million dollar improvement made in the past decade - I don't know the exact amount.
*** The Richmond BART station is the only BART station with a co-located Amtrak station.
Amtrak closed the station because the didn't want to pay any more cab fares...