A kitchen is a climate controlled space. The water left in a sink evaporates quickly. There is no acid rain or road salt in a kitchen, etc. Being outside is damaging to materials, moreso than just water exposure.

The average kitchen sink sees a far more challenging environment than you seem to believe. My kitchen sink sees acids, bases, salts of all sorts, and just about every manner of abuse. Boiling, freezing, and rapid changes in between.

It has nothing to do with environment. As others have mentioned, most kitchen sinks, like good "silverware", have a higher chromium content. The CT seems to have a low grade SS.

The (in)famous Delorean clearly used a better grade of stainless steel. There were no problems with Deloreans rusting, with people having said vehicles many decades later will zero body rust. That was specifically the #1 noted feature of the car.

> The average kitchen sink sees a far more challenging environment than you seem to believe. My kitchen sink sees acids, bases, salts of all sorts, and just about every manner of abuse. Boiling, freezing, and rapid changes in between.

Does your sink get coated in salt for weeks at a time? In areas where road salt is used, cars certainly do.

Cars parked outside will often still be wet after a nighttime rain, while water in a climate controlled kitchen sink rapidly evaporates. If your kitchen sink is still wet the morning after washing dishes, you’ve got bigger (mold) problems to deal with.

Even 316 ‘marine grade’ stainless will pit and rust, given enough time outside. I’ve seen it plenty, metal NEMA 4X enclosures rated for outdoor use are made from 304/316 SS, and those eventually rust.