Most are, or are very close like Frances 1.9%. IIRC almost everyone is at 1.7 or above.

Sure, better be at 2 but well...

It is much fairer to use GDP.

If a nation chooses to have lots of social programs the government would need to have a higher income. This would result in higher NATO spending target. A nation that doesn't spend on social programmes would likely have a smaller government income and a reduced NATO commitment.

Additionally how the nations government works may have an effect. If a nation has lots of smaller local authorities that raise their own money and spend it themselves (like US states) then the federal/sovereign government would have a smaller income. An income that doesn't really match the nations governments spending.

GDP solves this and makes it agnostic to government structure and policies. The stronger your economy the bigger the commitment you make. Countries with less GDP per person tend to have lower labour costs. So manufacturing and military wages scale well relative to the countries population.

Frankly, if Trump gets in again, all of Europe could raise their defense budgets to 10% or more of their GDP and Trump would still try to leave NATO, simply because he wants his Putin-sempai to notice him.

He also wanted Mexico to pay for a wall, framed Putin and other dictators as geniuses and friends, and aimed to make America great again™ despite pushing it to isolationism and irrelevancy.

Let's not take a single sensible thing he said as some kind of huge win, especially when this has been the stance of US presidents before him as well. The only difference is that now war is close enough to EU that western countries started to wake up about the need to defend themselves.