“$500 billion per year business” is a sort of meaningless term, especially in retail, when you compare to the fine.
Walmart’s operating income was “just” $22M with a final net income of “just” $6.7B (in the ballpark of large tech company quarterly profits).
It’s still true that a $330M settlement is then just 5% of their annual profit (and thus looks like that’s how the number was chosen), but comparing to their $500B revenue isn’t directly meaningful (though it is for your Polish GDP, sort of!).