Talk to someone who lived through WW2 rationing (I have). (Sadly, they're pretty much all gone now.)
Let's take WW2 gas rationing. People were allocated gas based on their profession. Note that this had NOTHING to do with their needs. So what happened? Nobody had an allocation that matched their need, it was either too much or too little. So what happened? An illegal black market emerged where those with extra sold it to those with less (at high prices, as illegal markets always carry a price premium).
Let's take your birthday cake example. It has the same assumption built in - that everybody wants exactly the same amount of cake. This is never the reality, and forcing it on people results in inefficient mis-allocation, and people who want more saying "hey, are you going to finish yours? Can I have it?".
> possibly asked in bad faith
You might want to read up on the history of the results of rationing before you draw such conclusions.
Let's take WW2 gas rationing. People were allocated gas based on their profession. Note that this had NOTHING to do with their needs. So what happened? Nobody had an allocation that matched their need, it was either too much or too little. So what happened? An illegal black market emerged where those with extra sold it to those with less (at high prices, as illegal markets always carry a price premium).
Let's take your birthday cake example. It has the same assumption built in - that everybody wants exactly the same amount of cake. This is never the reality, and forcing it on people results in inefficient mis-allocation, and people who want more saying "hey, are you going to finish yours? Can I have it?".
> possibly asked in bad faith
You might want to read up on the history of the results of rationing before you draw such conclusions.