It's a super common prescription and most doctors probably couldn't spell it offhand. Combined with dosing info it would be more obvious. Also if they do happen to be wrong it's unlikely to actually cause harm with acetaminophen/paracetamol.
Edit: another benefit is disguising to a patient that demands something to take. Essentially a placebo.
Pre-electronic records, yes they wrote a lot. Lot's of things were done in shorthand or with forms to reduce the writing. It's also that a doctor's time is valuable, saving 30 seconds on a prescription is a lot when you write 10s or hundreds per day.