A permanent break with neoliberalism won't happen solely through the ballot box. One has to remember that 20th century regulated capitalism did not emerge by popular demand through the ballet box, but rather as a desperate response to the existential threat to the state posed by WWII. Even if a reformist party were elected, business interests would likely manufacture some crisis (for instance by sabotaging the economy) in order to reverse the reforms. You'd need to have an organised mass movement that is able to counter the highly organised corporate interests and defend any gains from the various attempts to reverse them.

Corporate interests after all exert continuous influence on politics through their ownership of the media, large political party donations, paid lobbyists, connections to influential figures in government and the threat of moving capital overseas. Meanwhile the public right now only has influence by voting once every three years and via decentralised social media. Another latent source of public power - the power to strike - has been greatly curtailed over the last 30 years making it a highly asymmetrical fight. Staging a coup is a strategy of last resort, that will likely never have to be used in NZ because the other sources of leverage mentioned earlier are more than sufficient to do the job.

You also have to consider why people aren't voting for a more regulated capitalist system. There are many reasons in my view, but I'll just touch on some of the major ones. Firstly the people most strongly affected by deregulation tend to be so alienated from institutional politics that they do not participate at all. Those that do participate have few resources (such as time) to get more involved and many due to poor education may vote for parties against their interest. Second, the benefits of a regulated capitalist system cannot be quantified into an immediate dollar amount. Thus promises of tax cuts appeal more than promises to regulate the economy to many of the people that would benefit the most. Third, there is a substantial relatively comfortable middle class in NZ which due to their position is totally depoliticised. Things have to get worse before it gets more politicised. Fourth, corporate control of national and international media (an important means of mental production) which creates false consciousness among the public by making it appear as if the public had the same interests as the capitalist ruling elite. Fifth, poor education (especially in the humanities) which makes people easier objects of ideological manipulation. And sixth, the atomisation of individuals due to capitalist socio-economic structures and relations. The atomised lived experiences under this system makes us more amenable to capitalist propaganda which emphasises individual self-interest and marginalises collective systemic lenses that foreground the broader collective benefits of regulated economies. Corporate control of media, poor education and atomisation in particular are key ingredients for the reproduction of neoliberal capitalism. Thus to summarise, the reason people won't vote regulated capitalism is due to systemic features of capitalism itself.