I don't think what you're describing in your example is the Contacts app being taken out of RAM and having to reload. When you come out of an app a picture of the app's current view is taken and is used for the multitasking view, and also for the app opening animation.
If you go to your Contacts app, don't scroll, then press home button, then double tap for multitasking, that's a frozen shot of your Contacts app. Open it from there, and the image eventually gets replaced by the actual app. The two images should exactly the same, because in this short time it's very unlikely the Contacts app will have been taken out of memory.
What you describe with your scrolling example is simply the picture being taken not at the exact moment the app was suspended - it must be a few moments before. So when you open the app again and there's a slight movement, that's just the difference between the picture and the actual last view of the app, after it finished a little bit more scrolling. This could be improved by Apple I guess, so the snapshot is taken at the correct time.
When the Contacts app IS taken out of memory, it will be very obvious and more annoying, it won't change "slightly" as you describe, but a lot. The app will go back to the top of the list whilst your last screen shot will be in the middle or wherever.
I'm no expert but I think it's the developers of Contacts who've chosen to not save the scroll position when the app is taken out of memory. But they may not wish to in order to ensure users aren't stuck in faulty states even when they try quitting the app.
