We landed 5 minutes ahead of this Aeromexico flight and heard the ground controller give the crew a phone number to call for a 'pilot deviation' incident. Was wondering what all that was about until I saw it here.
Well, SFO was using 28L ILS and 28R ILS approaches during that time of the day so it may well be that Aeromexico had the 28L ILS programmed in the box and wasn't expecting 28R. Especially since they arrived on the SERFR2 arrival just like we did, which 90% of the time, will have you land on 28L as the SERFR2 links in with 28L ILS approach at waypoint MENLO. But rarely do you fly straight in to the approach at SFO as ATC will radar vector you all over the place, before you intercept the localizer for the ILS.
Complacency perhaps was to blame here and possibly not updating the box with the 28R ILS when it was assigned. That's my guess anyway.