Australia is one, New Zealand another. I can't speak too much for other countries I guess so I probably shouldn't have written "many countries" as that's just an assumption on my part.
I'm from the US, moved to Australia and am now a dual citizen.
I think the reason for this here is because we have preferences in our voting, and we have compulsory voting. I can say, "First the communist, then the gun people, and if neither of those, finally go for a major party." if that suits me. That means our voices get heard, and the major parties listen.
In NSW government for example we had an unpopular law put in place that killed our nightlife, so an entire political party was created just to fight that one law. They got lots of first preference votes, and the votes for all who did that were routed back to candidates that actually won because of the preferences. Being able to allocate our votes back to major parties with our voices being heard is important. Liberal then realised this wasn't a hill they were particularly keen to die on, so they repealed the law. (https://www.timeout.com/sydney/nightlife/keep-sydney-opens-o...)
Also, compulsory voting means that everyone is going to vote. They have to by law. So there's no need to stoke the base to get turnout. Stoking the base makes you scary to everyone else and you get the smack down at the polls for it.
We currently have Greens members in our house of reps, and many many 3rd party candidates in the senate. It's nowhere near perfect, but having your voice heard clearly, having that reflected in law, and ensuring there's no apathetic middle that lets the extremes dictate policy cuts the crazy right down.
We must know different people in NZ and Australia, because I disagree with the inference their citizens treat politics like the weather report. One of the biggest differences at least in NZ is that there exists MMP for voting, which allows NZ to avoid brinkmanship in policy and winner-takes-all mindsets that lead to sharp divides.
It's not quite that it's unimportant to people I guess, it comes up in conversation during election periods of course. People just aren't particularly partisan or passionate in my experience. I think most people have other things they would rather talk about.
Similarly as the comment above mentions, Australia has preferential voting which helps in reducing the overall divisivness of the two party system most democracies end up with.
