people are going to want convenience, frequency and reliability
KRA will be operating routes that NZ have abandoned due to their very high costs.
NZ have never really been a very efficient airline. Govt gave them something like $880 million bail out, but they are fat & lazy as have no competition on many domestic routes & also many international routes, esp. when you take into a/c the VA/NZ alliance.
BTW you don't need a lot of infrastructure at small airports with no security required.