It seems like it's a direct IT support position. Meaning that someone is supposed to be there ready to answer calls/problems from 9AM to whenever. Clients, whether internal or external do not want to call in at 9:15 and hear that they can't be helped because XXX hasn't come to work yet, especially when they've got an agreement from you that you will be open at 9AM every day.

If you are in support like that, you generally do need to be at work exactly on time. Same as being a cashier, factory worker, etc.

It's not like being a programmer, sysadmin, etc where exact hours typically don't matter much as long as you're available for meetings and the work gets done.