Why do people think we’re naive, dense or very unaware of real life? We can figure things out ourselves

I always get reminded of there’s still manipulation everywhere no matter how nice the environment is or if it’s Christian, some people won’t always be good or nice. Good things I do, me aunt and uncle has to remind me just because something or a place looks nice or Christian doesn’t mean the people will be like that.
My uncle said nobody is there to impress you. And you aren’t there to impress anyone.
My aunt says I need to think realistically because I’m not the best at noticing red flags or toxic people. This is why I need more guidance in these things than my neurotypical siblings. I always think everyone I meet is my friends and everyone will be nice and that’s why I always end up getting hurt.
I’m almost 23 and they’re talking to me like I’m 13 or 16. I’m AN ADULT!