Is this really that unusual? I feel like most places I've worked, as long as I made it to meetings nobody cared if I stepped out for an hour to run errands or something.
Extremely.
Lets obviously ignore the large percentage of the workforce that are waiting tables, stacking shelves, have to use a punchcard and have their hours tracked to the nearest minute etc. for whom stepping out for an hour to run an errand probably means they get paid a couple of hours less at best or fired if its done without the permission of their supervisor ...
Professional 'knowledge' workers - there are workplaces where its ok, there are workplaces where you would put your career into reverse at 100mph by not being present from 7am to 8pm for your 9am-5pm job.
Having worked for almost ten years now, I've always been able to take off an hour here and there without having to battle for it or come back with doctor's notes. When I was a contractor I'd generally have to tell someone and make up the time, but even then it was never a huge deal. Where I work now no one cares what I do at all as long as I'm reasonably productive.
Technically your work hours here have to encompass (IIRC) 11-3 I think? Or 9-3? Something like that. So no working third shift, I guess. But it's pretty flexible.
You'd be surprised. So many places it is not the thing. Or it is made hasslesome with team calendar update plus email to manager with justification and so on.