These aren't "NATO expenditures"!!!! They're the military budgets of NATO countries... However, the US defense budget isn't $1.5 trillion, it's $900 billion. The $1.5 trillion figure is a Trump proposal, not a reality: there's something complicated for you to understand called democracy, with a vote in Parliament.
Where is the French military budget ($67 billion)? Is it no longer part of NATO?
You have to compare countries relative to their GDP. It doesn't seem abnormal to me that the United States, with a GDP of $32 trillion, spends more than Poland. Poland even spends more as a percentage of its GDP than the United States...