Rhone

I think you've hit the nail on the head. In the end, people are mostly rational actors. Not having access to your phone/passport/money/credit cards/meds/... in a foreign country is a very unpleasant experience. If you leave them behind during an evacuation, do you expect to see those items again in a reasonable timeframe? If not, do pax think that the airline will help solve emerging issues (getting emergency travel documents, money, food, lodging...)? Note that even "losing" check-in luggage abroad for a few days can already ruin a trip, and that shouldn't contain any valuable items.

Unfortunately, pictures like the one shown above only reaffirm the intuition people have that they should bring their stuff with them. Most pax on the photo have all of their belongings and are on their way: you can literally see a girl with walking away from the scene with her suitcase and two bags while she's talking on the phone! Morally speaking, the pax who left everything behind did the right thing, but they are the "losers" in the situation: at best they will have to wait for a few hours while their luggage is being secured, at worst they will lose their valuables, incur a lot of extra costs and have their expensive trip ruined. (If you think about it, it's not unlike the famous prisoner's dilemma.)