I know you said the dealer did a brake job for you once the PPI was done. Fact is,this should have been done BEFORE the car was even offer for sale.
I saw the car coming off the truck, and my own inspection saw the pads at maybe 30%. I negotiated fresh brakes, had nothing to do with the PPI. PPI was to double check stitch jobs, etc. Peace of mind.
The underside looks no different than any other Subie I looked at, including local models. Undercoating intact, no rust, exhaust looks great.
Now, there are "rusty" models from the east, and I've seen a few. But, even from bone-dry Alberta, I've seen this. People that don't look after their cars live everywhere. I used to be severly biased against Ontario and Quebec cars, die to rust and the long term implications of salt usage. But, rust proofing has become much better on the last few years and even Alberta is salting it's roads now. We have to put up with paint that's smashed to bits from giant rocks poured on the roads. Sand? Where? GRAVEL. Combine gravel with water-borne paint coatings, and we have a province of cars with hoods that are chipped to bits.
Our Forester undercarriage looks no different than the no-winter-no-salt-ever Outback we bought from BC.