There's different grades of SS containing different amounts of things like chromium and molybdenum for corrosion resistance, though I'd argue the "stainless" aspect is basically bullshit for SS items that rust while adhering to their intended use. I have a few large stainless steel kettles that I've done some wacky things with, and neither has any detectable amount of corrosion after years of abuse. Not even anything like the relatively minor corrosion spots seen in the photos.
For a SS electric truck that's marketed as being not only rugged but "badass", it's embarrassing that we're already hearing about rust. It seems L. Ron Musk decided to sell a half-assed product so critics can't as easily point to it as a total failure.
That’s the right way to think about it - it comes in different grades based on the expected level of exposure to things like strong acids or bases but it’s not magic. You can especially see this in appliances where stainless steel was marketed as a premium product but the cheaper lines (or cheaply-made / expensively-marketed) are much less durable than the painted metal they used to use.
Darkroom chemicals versus natural environment? (Though maybe it's pollution or trace elements in organic materials causing the rust / pitting on the CT?).
Darkroom chemicals have varying pH, both acid and alkaline, there’s various salts involved, and there’s a decent amount of metal-on-metal contact in development tanks (you load the film onto a metal reel, and the metal reel goes into a metal tank, and they rub against each other).
Fair, 90% of my darkroom experience was a stat cam and we used plastic tubs and rubber(ized?) rollers. They always stained but since I wasn't using metal...
Steel alloys are not, in general, homogeneous. They are often composed of a microscopic mixture of different materials.