This highlights something about our industry that I find a little weird. Collectively we want to be respected as professionals, yet feel it's ok come into work whenever it pleases us despite its impact on the team.

In my view, a true professional shows up and gets the job done, no matter what. Asking employees to show up at 9 am on a reasonably consistent basis so that the team can work effectively seems like a pretty low bar to me (except in the case of special personal circumstances, of course).