Cut them some slack - PIN number is common enough. And in spoken language it might conceivably eradicate some ambiguity (PIN the number versus pin the pointy thing). Admittedly the context usually gives it away.
And we're using natural language, not a programming language, so it doesn't have to be complete:
- my car's passed its MOT --> MOT test
and it can be redundant:
- 5am in the morning --> 5 in the morning / 5am
- it's got an LCD display --> it's got an LCD