Capturing video with iPhone issues

I've been bothered since day 1 when filming with my iPhone(s) I've had over the years. I am not sure about the terminology (I'm more or less kind of a newbie..) but the colours of the movie has a tendency to flicker when the scene changes.
I guess it's kind of related to whitebalace/exposure but it feels very aggressive on the iPhone.

Try shooting a kid in the swings and you'll see color-"flickering". Perhaps background grass differs slightly in colour all the time because of "color-recalibration" (sorry for my bad terminology but perhaps you know what I mean).
Some apps allows you to lock "exposure" and this fixes the problem but may introduce other issues aswell unless you're filming a more or less static scene.

I have not experienced this colour-problem with regular digital-cameras. I've had a few (all pretty cheap models) but this problem has never bothered me, it hasn't crossed my mind until I started shooting family-movies with my phones.
The question is, what does regular digital cameras do that the iPhone doesn't?