You could have paid $300 while the person sitting next to you could have significantly more or less, depending on a whole host of factors.
Same with bitcoin: someone could have paid $1.50 for a transaction in the same block as your $9 transaction, depending on its size and how quickly the sender needed to have it confirmed. Someone also paid $.50 to be in that block but they were okay with waiting for an hour before it would be confirmed.
A dashboard such as https://bitbo.io will show you fee estimates.
I said $9 because the average transaction was $9, the median was over $5. If someone is paying $300 under those circumstances it is because they have a large, complex transaction. Transaction sizes vary, transactions costs aren't as random as you are implying.
> someone could have paid $1.50 for a transaction in the same block as your $9 transaction, depending on its size and how quickly the sender needed to have it confirmed.
That's not how it works. Most transactions are small, you can't somehow cut them down to a fraction of the size it takes for a basic transaction from one address to another.
> Someone also paid $.50 to be in that block
What transaction is what block are you talking about? I didn't mention a specific block, some have had even higher average transaction costs. Where did you see that?
> but they were okay with waiting for an hour before it would be confirmed.
Again, that isn't how it works. If you put a transaction fee that is too low, you wait until there are no higher value transactions for yours to be included into a block.