Second guessing your question away, I think this is not about collectivism or individualism, it is about sense and sentimentalism. The most collectivist thing one might be able to do in a world where everyone encounters the dying might be to tone down your reaction to death, so that fewer of those around you feel guilty about it. This may not be individualism, and in fact, expecting others to care about your dead may simply be selfish, if there is no chance that all the dead can be adequately considered.
You might want to look at this from a sort of 'Desmond Morris' point of view. What is the cultural and biological message sent by sensitivity to the dead and dying. I would suggest that it is a sign that one's lineage has the luxury of demanding unnecessary actions of individuals to protect the group. We carefully process the dead and dying because they are a public health risk. But sending that signal is unwise when it stops being true. At that point, it is equally collectivist to require this natural impulse be suppressed.
We like to think of the harshness of traditional masculinity as a form of individualism, if not outright selfishness. But from a point of view put forward by pacifist feminists like Starhawk, it arises most clearly in the context of the service of war, which is a gift of oneself to an extraordinary level of collectivism.
Putting these two (who would probably never agree) together, sentimentalism has a social purpose, and so does resisting it. The former sends the message "We have resources that will go to waste unless we share them", the latter sends the message "We need to ration logically, even if that logic is somewhat inhumane." They are both empathic, one directly and the other less so. But both are collectivist impulses, and both limit genuine individualism.
Returning to the original perspective, modern cosmopolitan society is, from Starhawk's point of view, brainwashed into an impending feeling that scarcity lurks around every corner, and efficiency is therefore required for the common good. So it chooses the path of limiting oneself prematurely, chooses rights over responsibilities, and delays attending to broader shared needs. But that is a communal position. It presses those with more idiosyncratic individual impulses to deny them.
These people are in line to get money, they have resources, they could spend those resources on removing the obstacles presented to those who are more subject to their externalizing impulses. But they don't -- it would not be efficient, there will just be more dead bodies tomorrow -- and they have the right to pursue their chosen responsibilities first. They are communally choosing to make a space where that right is honored. If one of them broke from the mold, they would all be less stable.
So I would argue that we are not already desensitized, or that everyone is, and the choice indicates something different.
As the documentary 'Cowspiracy' demonstrates graphically, those in prior eras would expect any grown man to be able to behead a chicken without a second thought. And most of our modern, cosmopolitan peers just can't.
At the same time, most ancient folks would never sacrifice their religious solidarity and walk past a dead body just to get something practical, unless under severe duress. Their shared responsibility to God trumps efficiency, the same way our shared responsibility to efficiency makes us explain away our natural revulsion as superstitious.
