A flat rate typically implies a set percentage of income, regardless of how much you make, with no breaks or reductions.

So, a 10% flat rate on someone who only makes $30,000 is $3000, while the guy who makes $5,000,000 pays $500,000.

Ignoring the obvious flaw of throwing out the importance of infinity here, they would be exceedingly unlikely but technically not unable. A random occurrence is just as likely to happen on try number 1 as it is on try number 10 billion. It doesn’t become any more or less likely as iterations occur. This is an all too common failure of understanding how probabilities work.