Pre 9/11 I went up front of a Mexicana 727 Tx to Puerto Vallarta. Just to say Hi. All three crew were unstrapped.
It's the stunning ignorance of basic Newtonian physics that bewilders me. Perhaps I shouldn't be surprised. Some of my first DC3 skippers didn't bother with their belts, and a fellow captain on a small regional airline disapproved strongly about having to wear a seatbelt in his car.