>>Redundancy!
>>
>>ICU Unit
>>ATM Machine
>>PIN Number
>>Tuna Fish (What other kind of tuna is there? Do we ever say I would like a Bacon Pig Hamburger Cow?)
>>VIN Number
>>and ...
>
>I'll give you the ridiculousness of ICU Unit and ATM machine, since the acronyms are 'spelled out'.
>
>Tuna Fish is part of the vernacular, I'm afraid, as is Cod Fish.
>
>But PIN and VIN are generally said as a word, so I guess people want to distinguish between a pin (a piece of metal with a pointy end) and a PIN by putting the 'number' after it.

I agree with Jim.

PIN was doomed and became"pin number" from the very start, although there do seem to be more people dropping the "number" nowadays, I'm pleased to note.
As for differentiating it from the metal artifact, I'd like to see someone "entering" a pin.

As for ICU unit, I remember I got flak a few years ago for mentioning the redundancy of calling someone a "CIA agent"