I would withhold judgment. With a 3-4 year old, as a parent, I can tell you you may not know that they need a break. Or that they spent all morning interacting at home, and are just trying to get out of the house and the kid into a situation they can catch a breather.

The _guilt_ I would feel looking at my phone as a parent is objectively unproductive when I look objectively at how much 1-1 time I have sunk into my kid. People need breaks, and if not the phone, it would be something else...