Neither do most european and particulary east european miltaries get wages even remotely close to US, While PPP works in some aspects like soldiers wages in terms of gear its often not quite linear.First there are foreign components and systems paid in prices higher than what US pays for them domestically and then there are economies of scale. F35 production for example is so streamlined that there are much less manhours involved into every jet asuming same complexity and baseline than in russia or china so some of that PPP is lost be being less efficient , Same goes for European production of jets like EF2000 or tanks like Leopard these are practicaly hand built ,lower wages in Europe do not end up making product cheaper, Ukraine trying to manufacture everything domesticaly will not be very efficient while manual labor is cheap material and tech imputs might not be .Besides economy so flush with foreign funds and low on manpower is not contusive to low cost labor in future. That one billion a piece Patriot is still one billion $ a piece.
In any case GDP to PPP factor today is cca 3.45 , so those 6billon $ , are 20.7billion $ PPP