I wonder if stickers in general are more common in the US just like bumper stickers are.
As someone based outside of the US, I rarely see people with stickers on their laptop.
The very vast majority of cars also do not have bumper stickers here (and those that do might have one at most).
I agree, in Australia you see plenty of them on laptops, water bottles and just out in the street like you said.
We do have a lot of stickers on cars too but it's more common to see them on windows of the car not the car body, and I think in general they're socially quite different to what you'd see in America. More like brand stickers and hobby stuff, or jokes, not so much politics or religion.
As someone based outside of the US, I rarely see people with stickers on their laptop. The very vast majority of cars also do not have bumper stickers here (and those that do might have one at most).