Post graduate students are merely slaves to be exploited by the oh-so-mighty advisors.
They slog like hell and often remain unappreciated for all the work they have done. Advisors talk to collaborators and spin up tonnes of bullshit, which in turn gets hurled to the students. The student works to get some sense out from the bullshit, and emails it to advisor. Instead of saying a THANKS (which is the most precious word in the entire universe, judging by how hard it is to get one to say it), the advisor sends to the collaborators directly. Without even acknowledging the presence of the slave.
The oh-so-mercenary collaborator thanked the advisor and forgot who was the one who churned out the data.
Maybe a maid feels even more appreciated.