Ah OP I feel your pain, it's so hard, but not all kids find going out easy.
Just imagine being taken somewhere strange and not having any idea what was happening and whether you would ever get home again! Adventurous kids may love it, but ones that like order and predictability can find it hard.
One of mine two to get really disturbed going away from home and scream cry and fuss constantly, from about 6 months onwards. Then we realised that even though she was not yet talking, as a PP says above, she needed to be told what was happening in advance and have the plans explained. What we would see, what we would eat, etc. And in particular, to be confident that we would be coming home again. And we used to go over it again though the day. "Look, there are the swings we said about" "Now it is time for the sandwices" etc.
If got easier and easier as she learned to talk and understand more, but e were really at fault for forgetting she needed due warning, sometimes
(She's still a real home body at 20 - even though she loves being at uni, there's not place like home for her still! She's really good at planning and organising too - I think it realy is her personality)
The other one was always up for an adventure, and still is! (also - he's a bit of a captain chaos - has to work much harder to keep on top of things)
Different strokes for different folks, even from babyhood. But if you can make his days out more predictable and understandable for him by explaining everything in advance, it could really help