I wonder if the total money we pay neurosurgeons is greater than the total money we pay burger flippers.
Conversely, if the teacher says, “Fred and Joe did poorly, so they will taken out back behind the chemical shed and shot in the head – unless of course you would like to give them a few of your marks to stop that from happening” you might expect a few more people willing to take the deal and still study for the next test.
School tests are a situation where (1) most people accept that outcomes are more-or-less earned rather than being random, and (2) consequences, at least in the short term, are fairly minor. This is probably why there is more support for socialism in the real world than there is when it comes to school testing.
This analogy is bizarre. In real life, the hard workers inevitably quit when they realize there is no advantage to working hard. For a little while they might be able to coast on the efforts of the suckers who keep working hard, but eventually enough people will realize there is no connection between effort and outcomes, so the entire society starts to suffer.
Or the government starts shooting people in the head for failure to perform slave labor.
… Not to mention the fact that now I am also in danger of being shot in the head, because Fred and Joe took all the marks that I needed for myself.
Not all your marks. Just enough so that Fred and Joe don’t get shot. You still have 80/100.
To make the analogy less analogy-y…
Suppose you make $200000/year, and Fred makes $5000 and Joe makes $2000, and pose the question, “Fred and Joe can’t afford food and will starve without help – do you support paying taxes so that the government can open a food kitchen that will stop Fred and Joe from starving?” you are much more likely to get an answer in the affirmative, than you would for the “analogous” question about school and marks. The difference is because school is, by design, a relatively consequence-free environment where failing means you get a stern talking-to about straightening up and flying right, instead of death.
What? 
Communism is appealing from an idealistic standpoint of making sure everyone gets their needs met. But it doesn’t work in practice. It depends too much on conformity of thought and deed in putting the needs of the whole against the needs of the individual. It doesn’t allow dissention or individual creativity. The problem isn’t you making $200k, and then distributing it to Joe and Mark making a lot less. You all get paid the same for doing whatever job you are assigned, regardless of your interests or abilities.
The main danger from communism wasn’t getting shot in the head unless you were a political rival. It was starving to death because you have a bunch of government assigned people working jobs they have no interest in and don’t know how to do. And since there is no “market” to set prices, no one knows what people should be working on or what they need to make.
I believe the point is that most people aren’t willing to share their hard-earned wealth with the less able in the name of “fairness,” or by official decree, but they’ll willingly share if it’s in the name of “altruism,” to save lives.
No, the point is that communism will share your wealth for you regardless if you want it to or not.