It does all come down to communication. I had bosses who travelled a lot. MB was great, called me or texted as soon as anything went awry. DB once called me from London saying he'd just missed his Eurostar when he was due home 15nmins later. Eh? what? just missed? Eurostar takes 15 mins since when?! He knew he was going to be late, had known for ages and didn't care to tell me. MB I was fine with, DB and I had issues.
Now we have a nanny we make damn sure we communicate anything planned far in advance (eg DH is deployed, I need to leave early so we need her to start early - this is agreed in the contract) and if there were to be unavoidable delays (cyclone alert, my car breaks down and DH's office is in crisis) I would let her know right away. To do otherwise is just unfair.
I get the idea of paying for flexibility (I feel we do) but that also goes both ways and we make it abundantly clear at every stage that due to DHs job we need more than most, and that shit does happen and not infrequently so he cannot be relied on, therefore if I have a problem it becomes nanny's problem (and I would pay overtime and bring her chocolate to apologise). The OPs situation wasn't an emergency though, just inconsiderate.
happy it's not worth being unhappy over. Look for a new job 