Got it treated by Krown rustproofing before the first winter, and spot treated with Fluid Film (lanolin spray) since. If I didn't drive on gravel so often it probably wouldn't need the yearly touch up.
1) better brands are really made... better in many details. I own second BMW, anytime I had a small scratch, got me worried it will eventually rust it all, technician told me not to worry, all outer surfaces are covered in zinc under paint. Compared to cheaper cars I've seen, there are literally many more layers of paint and other stuff before it comes to actual steel (or there is aluminium ie for some Audis).
2) where I come from, in cca eastern Europe with cca harsher winters, all sane folks who value their cars get right after buying get some additional protective layer on the bottom of the car (don't know details, don't live there but its not a trivial process). Easily lasts a decade. Back home during winter there is often salt and other chemistry used on the roads so without that, it would be bad much quicker.
If you live next to sea/ocean, you are screwed though I think, salt in the air corrodes almost everything.
Automakers that build cars for Europe have to make them better. A car will not pass a typical European safety inspection if it has any significant rust. In the USA many states don't have inspections of any kind, and the ones that do are often just emissions, or maybe include a quick check that the tires and brakes are servicable.
Nonsense. Most manufacturers sell exactly the same models in both Europe and North America, with perhaps minor tweaks for things like exterior lighting. Rust is mainly caused by road salt, and salt just isn't as heavily used in most of Europe.
Europe is a big place. You'd be surprised how easy it is to bribe the safety inspectors in some countries.
Just buy a decent quality car and make sure that it is properly undersealed before you takle it anywhere where salt is used on the road. Wash it thoroughly underneath as well as on top at the end of each winter; automatic car washes here in Norway do that for you.