I'm in the UK and used to live by the sea. Any exposed metalwork (or thinly painted) would rust quickly as air is filled with salt all the time.
Corrosion or rusting is an electrochemical reaction requiring oxygen, water and an electrolyte like salt (to allow conduction to take place). The warmer the water, the faster the conduction (corrosion).
Some hard tap water has salt present, so I've always used car wash with rust inhibitor in it. That helps a bit. I also use car wax in places and ACF50 on bolts and difficult exposed areas.
I've also riden brand new bikes through winter salted roads and they take weeks to rust badly if you leave salt water on them, for even a few days in a garage. So months would look really bad. Once that paint coating is breached it'll rust very quick.
Salt damages bikes quickly if left unattended and will damage alloys (oxidization), chains, bolts and steel frames quickly even when washed regularly.
Its why Road Bridges spanning salt water need to be painted constantly to prevent corrosion.
Your pictures look like salt damage to me. Where a bike has been exposed to sea salt, from the air, riden on the beach, or riden through wet salted conditions. Just wet roads near the sea will be enough.
I've also had alloy framed fairing bikes like VFR1200 that weathered well (except brakes siezing with salt damage). So some bikes are built more hardened to corrosion naturally from materials used.
If salt exposure, must wash it immediately with cold water (not warm water as it expedites the electro chemical reaction with salt). Even then once salt takes hold its difficult to stop rust.
At the end of winter I have to regularly go around and repaint (touch up rust spots) on my steel framed Bandit 1250 with black smooth direct to rust Hammerite paint. To keep on top of it. Its the way it is.. not quite a road bridge but same principle.
Salt, water and bikes dont mix well.
Just my experience.