Originally Posted by
1.3vso
Going by the video, it looks like the catering truck was eastbound in the vehicle travel lane and crossed the taxiway before coming in contact with AeroMexico. Probably crossed well before the B737 entered the taxiway but had to stop for traffic ahead (probably giving way to a plane on a taxiway further east) not realizing they were encroaching on the taxiway behind.
The above was my assumption as well, traffic ahead stopped so the truck stopped hanging out in the taxi lane.
Taxiing in LAX is one of my "highest threats", the brief mitigation= both heads outside and on a swivel at all times.