Would your colleague be lucky enough to drop her child at school if you were all back in the office, or would she have to leave home a lot earlier to get into work for 9am?
I feel like this attitude is where it has all been going wrong for years. It shouldn't be 'luck' to be able to drop kids off at the appropriate time. Will the working world end if folks aren't logged on until 0915? No, of course not.
We're just all so trained in the 'clock on clock off' idea that if you're in 9-5 you're working productively 9-5 and everything else in life (caring, kids, medical appointments, etc) comes second to this, that we're making life harder than it needs to be.
Nobody is fully productive for 8 straight hours, so why not be flexible and remove stresses so people have a chance to work at the times when they are more productive?
My DC have only been in school since the pandemic started, but I start work at 0600 (usually, today my broadband is down 🙄), sort the kids when they get up then start again after the morning school run. And it's fine, for the team and for me. Another colleague does different hours on a Tuesday so they can help a friend, that also is fine.
I do wonder if there's a perception that anyone not doing 9-5 is doing 'less' or getting special treatment? In reality they're not but I guess some people don't like change/feel mistrust of difference.