‘Stainless’ is a misleading label; this type of steel does get stained, but it does not corrode.
That is unless it comes in contact with concentrated bleach.
This is why it is important to clean your stainless steel trolley, but not with harsh chemicals.
Some substances discolour stainless steel, so it may appear rusted, but it is not corroded.

This is known as tea-staining, but it does not affect the lifetime of your stainless steel trolley.
Things like bleach, smoke, salt, heat tint, and harsh water typically stain stainless steel, damaging its aesthetic value.