Clearly NZ isn't marketing itself to the rest of the world quite the same way it is in Australia. If you say New Zealand in Australia, skiing is pretty much the first thing that comes to mind, but it's the least guessed answer here.
There are ski resorts outside of the Alps in Germany most noteably in the Black Forest, the Erzgebirge, the Bavarian Forest and the Sauerland but these resorts are rather small with only a few ones having more than 5-10km of slopes.
Unlike famously mountainous Australia... Okay, I'm being slightly facetious. Australia may also be mostly flat, but it's also about 23 times the size of Finland. That said, the vast majority of Australia's ski fields are concentrated in a very small area: the Snowy Mountains of the NSW/Victoria border. There are also two in Tasmania, but that's it. The rest of the country is flat and almost entirely devoid of snow. There are some great sand dunes though.
Andorra is 24 km across at its widest. You'd have to have criss cross the entire country 13 times in order for it to make the list. Even if the entire country was a singular ski resort, you'd have a difficult time physically fitting 334 km of ski slope in the country
As jankapr already pointed out, Andorra is very close to the 334 km that Finland has, and being there I can tell you that they still have a lot of room to "make" new slopes.
I agree with brettski. The problem with measuring by distance of runs is that what counts as separate runs is subjective. If there's a large, open bowl, as there often is at ski resorts, how do you classify that as separate runs?
I'm surprised you're surprised by New Zealand, the country is basically defined by one long snowy mountain range and skiing and adventure sports is the focus of its entire tourism industry.
Wow! Surprising that Slovenia isn't there, don't know if that's just me being stupid but I'm pretty sure they have a few resorts there. France and the US are tight, would of thought France would have slightly more but there we go!
I think this quiz could be updated once again, some countries are improving there ski fields very quickly and may appear in this top : bulgaria, montenegro, andorra, china, kazakstan for example.
Actually, to be fair and looking at the Olympic results at the moment, I don't quite know where all the French are either