At now with 2, I can only use one, so I wonder (I mean, if I use it, I lose time with the other, as the game engine can't fly them in same time).
Or surely there's something I missed.

I may have misunderstood but the main reason would be to have multiple teams at different bases? I have low level team for trading, the 'A' team for quests and mid level team(s) for haven defence.

But the UI is not made for this, as as soon we order to move, the time goes by.
So the UI is not made for having several squads, as only one is moving while the others are standing still.

I guess this game is badly disigned, like about the forbiddening of seeing our items by proficiency, it's only by classes.
It feels amateurish.

All the vehicles can move at the same time. If you pause you can then queue up all the actions and stop pause. Where it says 'Manticore 1' you can cycle through your vehicles and give them commands. I often have several squads going to different locations.

The weapon proficiency is a bit frustrating as you have to view all classes to see everything , By proficiency would make it much easier. I'd also like to hide older weapons that have been superseded by new tech.