Uhh - heard of math? When the US GDP is so much larger than any of these other countries, then why wouldn't its 0.7% be larger than the contributions od others?
Indeed, in
absolute terms, it would be - as a
percentage of GDP is isn't.
Of course, if the US had a "Flat Tax" (which a lot of "conservatives" say is much "fairer" than the current system) of (let's say) 10% then wouldn't someone who earned $100,000,000 "pay a lot more" than someone who earned a mere $50,000?
That would, obviously, grossly unfair so the only "fair" thing to do is to have everyone pay exactly the same amount of tax as everyone else?
That would work out to (roughly) $12,000 per person and would leave a family of four with the statistically average "household income" of around $52,000 with a total of around $4,000 per year to live on. A single income family of four where the income earner was paid less than $22.43 would, of course, have less than $0.00 per year to live on.
The funding formula, like the funding formula for the UN, was the funding formula that the government of the United States of America insisted on.
Now here is a fact that you might not have noticed. The total 2017 budget for NATO is $2,334,000,000 (military $1.38 billion, civilian budget $252 million, and NSIP $704 million) which is roughly 0.38% of the TOTAL US "defence" budget (it's also roughly the cost of 23.3 F-35s). Canada spends $15,500,000,000 on "defence". Is $15.5B more or less than $2.334B?
What people are talking about is not "spending on NATO" but rather "spending on their own defence" and there is no "international agreement" that every country in the world has to rely on what the government of the United States of America says is needed to defend themselves (based on what the government of the United States of America says the "threat" is).
In terms of percentage of GDP spent on "defence" the US ranks as number 11. Both the PRC and Taiwan spend less than 2% of their GDP on "defence" (and, in fact, spend the same percentage of their GDP on "defence" as does the UK). Algeria spends more than double the percentage of its GDP on "defence" as the United States of America does.