The vast majority of scientist, by your standard, don't really understand science. Humans have certain built-in biases and consistently make certain kinds of bad judgements. Even statisticians and mathematicians make common errors of judgement. The fact is that people are often not rational and are driven by emotion, biases, and other non-rational factors.
While it's useful to study and understand these biases and it's healthy to try to avoid commoon errors of judgement, it's not accurate to declare that anyone who acts irrationally is not truly a scientist or doesn't actually understand science. You are merely observing that they are human.