Its not clear to me that NZF has the funds to pay more often.
They probably don't re AWs and this year the FFs (who in massive contrast will play at least 11 times in 2019), Mens U20's & Mens U23's are all taking precedence over AWs.
It's crazy really that Wood, Marinovic, Smith, Wynne, Tuiloma - and many of the other first choice players haven't now played for the national team in over 18 months. Even Wood after a longest club season, must be itching to play for NZ in a game or two again.
I see AFC still haven't formed a Nations League (UEFA, CAF & CONCACAF all have). The Global Nations League is a pet project of Infantino's and one of it's supposed goals is apparently more internationals for minnow nations like NZ. So sooner FIFA put pressure on AFC to create a Nations League (which hopefully the OFC nations would be added to) the better.
But still I'm not sure that even that, would have stopped Boyd trying his luck with the Yankees. Regular games against likes of Mexico & Costa Rica - plus the odd high profile friendly (USA played England & Italy in Nov last year) - compared to playing Malaysia, Singapore & India.
If he cracks the Team USA side and goes well, it can only help his profile & club career. All comes down now to whether he's good enough to do it.