the scientific term, in english, is reciprocal altruism and came about a bit later, but does have origins in kropotkin's work.
i'm being lazy in sourcing from wiki, but this is fine for an easy concept like this:
In evolutionary biology, reciprocal altruism is a behaviour whereby an organism acts in a manner that temporarily reduces its fitness while increasing another organism's fitness, with the expectation that the other organism will act in a similar manner at a later time. The concept was initially developed by Robert Trivers to explain the evolution of cooperation as instances of mutually altruistic acts. The concept is close to the strategy of "tit for tat" used in game theory.
the reciprocity is key. if there is no expectation of altruism in return, it is not mutual aid, it is christian do-gooding.
and, what is the expectation that these people will receive something in return? there is not one. they're donating their time, in a market economy - and one in which labour is scarce. this is an affront against the working class!
if people are going to do these kinds of behaviours for strangers in a market system, they should expect a pay check for it. it is labour.
