Why do you need personal assistant at arrival? They cannot arrange you through immigration faster but standing with you in the border control line. I would not like that if someone just stands with me, because First class/HON passengers can request it, without any reasonable cause. You collect your luggage where the First class/HON tag is next to the belt.
Absolutely nothing in MEX on this week at departure and I did not cared. A few people in front of me in the security and no border control, immigration card will be attached to the boarding pass and collected at the boarding procedure.