"Ignorance is bliss" is a pretty big theme, y'know.
Jun shoving down his friendship agenda onto every Cardbot he meets (unintentionally trying to make the sealing/capture seem less scary or a bad thing), Uncle Iron isn't happy about this.
Due to the number of Cardbots around, Jun can't tend to all of them at once. He can't hear all of their troubles or doubts personally. The more the merrier = less attention individually. This leads Jun to overlook BC's own despair.
Jun's a kid. He doesn't have the emotional or mental capacity that's on par with the majority of his robot friends (assuming he doesn't, since exploring oneself in depth never really took place due to the episodes being only 11 minutes. They can't fit everyone's backstories in there).
I feel like Jun has a general assumption or a prominent view that friendship solves everything. No matter how bad it looks, surely with the power of friendship, they can get through it all together. Whether it'd be physically, mentally, or emotionally.
Later on in MCBW, Jun is slowly trying to improve. Thanks to Uncle Iron, Jun realized that their beliefs will probably never align perfectly, and that's okay.
Imagine if there were more Cardbots. And this kid was learning how to be more thoughtful; he's going to burn out from exhaustion for trying to be a very good friend to all.
BC reminded him. His very own existence reminded Jun of his "ignorance" (Jun never intended to be ignorant). Sometimes when BC tries to open up and tell Jun how he feels;
Personally, PERSONALLY, this is an example. The usage of "I'm here with you!" as a response to one's trouble. I'm not saying Jun did anything wrong here; in fact he's doing a very good job at comforting BC. But consider this, will that response be enough for everyone ?
What if they just stopped there. What if BC undermines his own despair by telling himself that Jun will always be there, using that singular assurance and nothing else. WHAT IF THAT WASN'T ENOUGH TO COMFORT HIM IN THE LONG RUN.
BC never went beyond to take care of himself. He assures himself that with Jun and his friends with him, he can take it. Take on the burden. Because. That's what Jun said. With the power of friendship, yeah, they can do anything and everything.
"I'm here for you" response wouldn't work on everyone. Someone needs a different type of reassurance or a way to get/feel better.
Even with BC, who was Jun's best and closest (robot) friend, Jun didn't dig any deeper. It wasn't his fault; he didn't know any better.
