Having multiple kids can make things much harder too. A child that is easy alone may not be easy with siblings.
Parents flex for children because there's a lot of things we don't care about. Little Timmy wants to go first? That's fine. But now introduce Little Jane. Little Timmy can't always go first. Now he has to contend with Little Jane.
Turn taking is the standard here. Doing it at preschool is one thing, but in every day life, at home, from sunrise to sunset, when tired or sick, is another thing. There's also lots of corner cases to navigate. What if Little Jane wants to watch something that scares Little Timmy? What if Little Timmy missed a turn because he had soccer practice? And so on.
You also aren't in control of all turns. For example, birthday parties. Or frequency of seeing friends. What is seen as unfair parts of life by an 8 year old can be completely out of your control.
You can oftentimes rely on the older one being a little more flexible than the younger one, and that is a life saver. As a parent you can lean on it and reason with them. But there is a scenario where this falls apart: twins. Congratulations, have fun reasoning with two 1.5 year olds who want opposing things.
The corner cases from taking turns can get easier as they get older though. I usually offload it to them: you guys figure out whats fair, everyone has to agree, let me know when you figure it out. This can degenerate into the most stubborn winning though, so I still have to monitor the results and stop relying on it if that's what is happening.
I dunno, it feels kinda exhausting for being easy.