[notabee]

People's circadian rhythms change over the course of a lifetime very considerably. Trying to keep all age groups on the same schedule is actually a pretty bad idea. Check out the book Why We Sleep. I think especially how we treat adolescents, who are usually late shifted by 2 or 3 hours compared to adults, is going to look barbaric in another 30 years. People think that 9 AM is a "late start" for high school, but it should probably be more like 11 AM. Even the ratios of NREM versus REM sleep change a lot over different age groups.

[AstralStorm]

Additionally, sickness, including common cold, can lengthen sleep enough to make it unreasonable to get to work early, and forcing (mildly) sick people to early work getting them further sick is an accepted practice.

Or running civic services 7 AM - 3 PM which makes it impossible to schedule without a free day or understanding boss. Something that should be available with perhaps only a minor downtime works only for a few hours.

The cumulated morning/evening hours tend to overload transportation facilities too.

[LameRubberDucky]

I'm with you on all of this. It was an eye-opener visiting other countries (USA native here) that were more laid-back about getting to work and staying at work. Mexico City in particular was nice and relaxed when I worked there for a while.