You got some good answers but remember too, you're only seeing a fragment of those kids at your place. The screen might for example be a special rare reward for them to keep them quite so your friends can visit you... doesn't mean they're on scree s all the time.

My kids aren't particularly screen born most of the time, but when we're out I often relax the rules to keep things smooth. The fact that it's a rare treat makes it even more effective