Welcome!
Now, I gotta be honest, this may look harsh but we’re only trying to help you understand.
I’m sorry, this shouldn’t happen- At all.
Here are some examples the manual has:
G2- V5RC is a student-centered program. Adults should not make decisions about the Robot’s build, design, or gameplay, and should not provide an unfair advantage by providing ‘help’ that is beyond the Student’s independent abilities. Students must be prepared to demonstrate an active understanding of their Robot’s design, construction, and programming to judges or event staff. Students should build, design, and code the Robot with minimal Adult involvement.
G4-Each Student can only belong to one Team, and all work must represent the skill level of the Students on the Team. Each Team must include Drive Team Members, Coder(s), Designer(s), and Builder(s). Many also include notebooker(s). No Student may fulfill any of these roles for more than one VEX V5 Robotics Competition Team in a given competition season. Students may have more than one role on the Team, e.g., the Designer may also be the Builder, the Coder, and a Drive Team Member.
And some mentions the Forum itself has,
Okay- I get that last one is not from our season. But it kind of tries to make a point. It is OKAY for students to start off somewhere but they gotta build off that. As you described “We designed robots together and coded them together, so our teams were basically the same.” would be against the rules generally.
Now- I get most of these are centered around adults and you may have not been taught this by an adult and walked over to the same solution as the 3 other teams but- You should’ve read the manual- At least to get a small understanding.
It’s okay to start off learning together — that’s literally how everyone begins. But when it comes time to register as separate teams, each one needs to branch out and become their own. You’re supposed to grow from shared ideas, not just copy/paste the whole thing.
And yeah, I saw your question:
Now, let me explain G4 to you, this means that you can only be in ONE team, no giving them your whole code.
Your header question makes that sound kind of like a joke " Should people who learn vex outside of school be allowed to team with people from other schools and share designs?"
You can, but you can’t give them literally everything, teams are supposed to be unique.
Now- If this doesn’t make sense let me give you some real life.
I’m in a schooled team with 4 other teams at my school. We all work in the same room, have decent interactions, and share eachother’s pities.
But- our robots ended up all completely different, how is this?
We all worked in the same room- Like I assumed you did- We all talked often- As you said- and we shared eachothers designs- As you also said.
Here’s what we did differently:
We talk to OUR team, come up with ideas with them. We time-to-time would gloat about how ‘great’ our idea was to other teams but nobody really tried copying eachother- Now, end of season, we build what we had in mind. Maybe some adjustments, like 3 more intakes than needed or a larger gear ratio on certain places- But still our idea- And the other teams, totally different. You’d wonder how they make it through the matches- But they do- And do it great.
You got to get creative, you guys need to learn a little personal space within eachother- Sure, Megan’s (thats gonna be out default) idea sounds great! You’ve got to get creative. Sure, Megan’s idea might be amazing — but that doesn’t mean you hand it out like free candy. Add something to it, reshape it. Don’t just drop the same bot on three fields and call it a season.
And code too — once you’ve shared the design and the code, it’s basically the same robot. May as well be on the same team. That isn’t what VEX had in mind when it created all this.
My apologies if I was all over the place. Here’s your mainkey points I want you to take home
-Read the manual
-Be creative, don’t fully take ideas from other teams- Adjust them
-Let’s avoid sharing things to people outside our teams when we know it won’t be changed.
Again, I hope this wasn’t harsh (and I hope I wasn’t too complicated with how unorganized I was), I hope next season you’d be able to get to go to the US. Just follow the rules and you may just be fine 
