I'm not sure if it's still the same, but as recently as three years ago there was no security on commuter flights in Alaska (part of the US, last I checked). I was gobsmacked to be able to walk straight onto a Twotter for a flight ANC-ENA and a DHC-8 on the return.
As for domestic security in NZ, I certainly had none on an ANZ Q400 flight last year AUK-NPL.
Pretty ironic that on some sectors security seems to have gone over the top, while a blatant lack of security still exists on others.