They have, but I'm not even convinced that's the result of the choice to seek the post-war US hegemony and Pax Americana, that's been a significant benefit
to America. The US doesn't have to spend that, she chooses to. Drop rate to the Nato agreed 2% of GDP as well and
still be the world's dominant and most advanced military power. Halve spending and the US would still reach the old two power standard in terms of spending -
easily. It would be nearer a 3 power standard. Right now it's more than what, the next seven or eight combined?
Germany has constitutional limits placed on her defence demanded by the post-WW2 allies, even if they did spend more. There's limits on when and how they can operate outside of Germany - though I'm very unclear on the detail. Holland may not have much navy - but it certainly still exists with frigates, submarines and what have you, and plans for new vessels - just rather few of them. They recently increased budget to get nearer that 2%. They've a population of about 15m, I think a modern carrier is simply out of reach without completely unbalancing their defence budget. They're way past their projecting power era anyway.
I do completely agree all signatories should stick better to that Nato agreed 2% though, or any future agreed amount.