I think it’s because everybody’s got an opinion about anything smile emoticon I think in the case of Science, it’s perceived public trust. People expect a lot out of Science and they expect Science to behave EXACTLY as they were taught it would.
Science isn’t immune to public opinion, neither is any field really. Even public opinion is subject to public opinion smile emoticon
Also, I think it’s because money is sometimes on the line. “Are we getting what we paid for?”
Of course it’d be best of Science was left alone to do Science. That’s what it does smile emoticon But a questioning public will continue to question. Such is what *it* does smile emoticon