As a former dweller in the Frozen North, I'm all too familiar with rust due to snow melting chemicals.
The newer cars seem to use some form of plastic for many of the body areas that used to be prey for rust. No metal, no rust. Works for me
The 'double galvanizing' some are so fond of mentioning isn't the dip galvanizing of old. Basically, body panels are exposed to a zinc mist. Some decades back I saw Fisher Body scrap panels where a similar process was soft enough that it could be removed with a fingernail. On the other hand, that was almost 30 years ago and I was looking at scrap parts. Knowing GM, they were probably figuring out how many molecules of zinc they needed for a miminally rust resistant finish. Hopefully, things have improved. The appearance is much better.
I used Rustoleum Undercoat spray cans on my '14. Most of the underbody aero panels come off easily and the exposed metal was coated with an additional layer of protectant. This was particularly true of the inside of the two 'unibody rails' that run lengthwise near the driveline tunnel. If those go, your car is scrap.
The front A arms need coated inside. I also made sure I did a good job on the rear suspension arms too. You can't buy replacement parts for what a couple cans of undercoat cost.
FWIW, I stopped my work when I spotted what I thought was rust. Turned out to be red body sealant factory installed during assembly. The dealership mechanic asked me about the undercoat and when told I did it, smiled and said "Finish the job".
BTW, I used a similar product on my 1992 Toyota, bought in 1994. I turned it over to my son when I bought the Forester. The only rust is a wee bit on the edge of the front wheelwells. Front fenders are cheap.