This is how my 8-year-old works on her school Chromebook. And all of the kids at her school that I've seen using laptops are similar. Touch the screen to interact, type on the keyboard. I think they're just wired to believe every screen should be touchable and go with whatever is easiest for them in the moment.
Huh that's really interesting because my 12 year old has been using a school-provided chromebook for 3 years now and she and all her peers almost NEVER use the touchscreen, they use the trackpad almost exclusively. And I've watched her using her ipad too, and she uses the touchscreen when she's in (her words) "that kind of app" but if she's in Google Docs she's 100% trackpad.
A touchscreen is a way more natural and intuitive interface than a mouse cursor driven by a trackpad.
If I'd never used a laptop before I'd probably do the exact same thing as the kids!