“The 9[am] to 5[pm]” is a common term for one’s regular job, on the basis that normal people start work at 09:00 and finish at 17:00. I’ve worked a few jobs and closest I’ve ever gotten to this is 08:00 to 17:00, which I gather is standard.
Are there real jobs where people actually start at 9 and finish at 5?
US Midwest 9-5 jobs are normal even when not really sensical for all businesses. Very much a control and “you sit here cause I pay you to.” I worked a place that expected 8:30am - 5:30pm with an hour lunch break. Salaried work. I worked hourly at a distribution center that was 8:30 - 5:00pm with half hour lunch.