Occasionally, if someone is thoughtful and open-minded, I think productive discussions about "taboo" topics can be had at work, but they're definitely the exception to the rule, and usually it takes until day 3 or 4 of the trip before we bring it up. If someone starts on the first leg, you can tell it's pointless and counterproductive.

Personally, I think our unwillingness to politely discuss and disagree about certain subjects has led to our collective inability to engage in intelligent discourse.