Firstly, I have worked for the past three years as a software developer. I've had to deliver things to a manager, figure out exactly what a client wants, and work collaboratively. I think that I've at least had a taste of the "real world".
Secondly, the idea that I lack some kind of mental capability to "understand or imagine what is possible outside of the school" is deeply flawed, and frankly unfounded. In fact, the condescension that arises from this statement is exactly the kind of attitude towards children that discourages them from taking risks and exploring independently.
I hope the next time you talk to or meet a 16 year old, you don't assume that they lack any ability to understand the "real world".