My DD had a brief and wonderful period (between 6 months and 9 months) of sleeping through from something like 9-6. I forget the exact hours.
Other than that (she's 2 and a bit now), she can quite happily go from 6am to 11pm with no nap. And then again the next day, and the next.
At the moment I rejoice, because her normal is something like 8-10 until 7, and it is absolutely fucking wonderful, and she's even decided to throw in some naps.
But please ... if you have a child who sleeps, even if you think it's obvious why they do and you see that the rest of us are fools, be kind.
Yes, on those days when my DD sleeps in to 8am, I should probably wake her.
Yes, on those days when she comes back from nursery at 6 and falls asleep in the car, I should definitely wake her.
But bear in mind that means I went to sleep past midnight, because I had to finish working after she went to bed. And then she woke at 2, and then at 4, and then got up at 7. If she napped, I will have been awake working. So, when at 6pm she falls asleep for half an hour, I will usually have had something like 6 hours of interrupted sleep in the past 24 hours. And, because it's been going on for a while, and I don't have the option to switch off when she switches off or to doze while she watches TV, I will be shattered.
And I reckon if I am shattered, mums of twins or multiple children or children who really, really, really don't sleep, must be existing in zombie land.
If you really think it's all as simple as saying 'put them to bed earlier,' fine, say that, but also listen when the rest of us point out we're probably trying to stay awake and work, too.