Because they’re never taught or encounter the notion that its fun to be wrong and learn more to correct and be able to speak more confidently in future.
I love when people correct me and we have a little discourse and the truth-seeking function of this format is satisfied in the end with everybody playfully (or sometimes testily but still vaguely good-faith) cross-examining each other and leaving space for learning and retaining space to allow people to revise when they are genuine in their attempts to understand.