Seriously though, those parents, However much you dislike them, are "entitled" to park as long as they like. That's they saying how dare someone stay parked in a full car Park all day because someone else is desperate for a space. They are entitled. No amount of slagging them off is going to change what they do.
So, your only option is to consider what you can do to change the situation.
You say it's impossible to change your morning routine, fine. I find it strange none of the schools offer a breakfast club, thought that was the norm these days?
Have you spoken to the school? One option may be school correspondence to ask politely that parents don't linger. Secondly, maybe special allowance, so you can use the staff car park, or your daughter starts 5 minutes later.
How do other parents manage, I assume several have children in both schools?
Do none of your children have friends that could maybe go in with? How far do you live from the school?
My children's last school was a nightmare for parking, people just had to walk or be early (or late).
Why does your eldest not have any friends? Is it a different school from the usual feeder school? If so why did you chose this one? Do you know anyone in the area? As in can you park outside someone's house that You know?
I just find it odd that this situation has yours so riled up, but there are no solutions. Obviously I'm an ideal world you could just park but that isn't the reality for a lot of people, so it's not exactly unique. I've had a child have to have a taxi to and from school so I know the realities can be different and complex. But, you can't tell people they can't talk and go about their business because you need their space, life doesn't work like that.
You can perhaps campaign the council to make the spaces drop off only, and maximum 5 minutes, but until that point you can't expect others to Move just because you need a space.