Virtually everyone struggles with it to some degree, some of the time. ADHD people struggle with this to a high degree, all of the time, to the point it interferes with their ability to function, and causes no end of anguish.

It's like accidentally giving yourself a small burn when pulling things out of an oven, vs. having a 2nd degree burns on half of your body. Technically the same thing, but scale matters.

This is also something that has crossed my mind. In the early days of my diagnosis, it was a challenge to explain that I even had a problem. People would (rightfully) say "isn't that basically everyone?" and I would have to struggle to say "yeah but mine's worse. I'm diagnosed." It was a real drag at the time but nowadays I'm kind of thinking maybe they were right.

No when you have ADHD it's really really hard to get started on a new task, but you do obsess over a task once you get started on it.

You'll do everything you can to avoid it first though, until the stress of the deadline overweighs the dread to start.

I always find that portion of ADHD somewhat amusing. Getting fixated on a task and unable to context switch is a big thing, which I think is surprising for many people.

One difference is sometimes being unable to even do things that one actively wants to do. Unable to focus enough to do hobbies or read a book.

That's not ADHD. That's normal.