One might argue that in a communist or otherwise "leftist" system, conditions of payment would have more to do with a rational assessment of the situation, rather than as a trade. The sherpas being paid in spite of not having done the work they had contracted for, due to some mere unforeseen circumstances, being a good example of the former kind of reasoning.

Whether a communist system actually would or could operate in this manner is probably best left as an empirical question.