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.

Agreed. When I was younger, for multiple reasons but mostly stupidity, I was 30m to 1h30 late at work every. single. day. And the official work day started at 9:30am, so it wasn't that bad to begin with. In my defence I must add that I never left before my full 8 hours were over.

I was in good terms with everybody, managers as well, and I think in that stupid age I did some brilliant work I'm still very proud of. After a couple of years, when all the rumors about me being hired fulltime were materialising (I was working for them through an agency), they just decided to let me go.

It hurt at the time, but it was a good decision that served me as a lesson[1].

Employers, unless you're a bank with set opening times, don't fret over 10 or 20 minutes. Programmers are productive only in a stress-free environment. Obsessing over 10 minutes is the total opposite of that. But please fire engineers like me, you'll do them a favour.

1: I stopped being so late in future jobs, but I also discovered I have some kind of DSPS. It's still bad, but I'm now a freelance (in Europe) working for US companies, my clients are having their coffee when it's 3pm here.