Maybe that little girl normally loved daycare. Maybe she was frustrated because she wanted to wear her fairy wings or because there was no Nutella for her morning toast.
She may not have been protesting about being forced to spend most of her waking hours in a loud daycare centre among strangers, with grimy plastic toys to fight over and a cold equivalent of a prison-yard to play in.
Yet, on her behalf, I felt like crying. I wanted to tell ol' yoga pants to listen to her daughter. To take her feelings seriously. I wanted to tell her to make sure her daughter did not feel invisible, invalidated.
Instead I kept walking to my class, where I learned some more terribly uncomfortable truths about child development.
I learned that Daniel Stern, an expert on mother-child bonding, found a mother's instinctual focus on and devotion to her infant were critical to the child's development.
I learned that the legendary paediatrician Donald Winnicott encouragingly said children don't need a perfect mother, but a "good enough" mother. But he found for the infant to begin to develop a capacity to experience a relationship to external reality, or even form a conception of external reality, to start with the mother must have total empathic atunement to her baby's needs. Later the infant learns to tolerate frustration. Even then that needs to be a gradual process.
Winnicott said: "Not having to react is the only state in which the self can begin to be."
So we learn all this theory about human development, yet out in the real world, well, it's hardly optimal is it? It's like we don't even know this stuff.
Little children, babies even, are farmed out to for-profit childcare centres, sometimes for 10 hours a day, because their parents have to go back to work, to become productive economic units. Is this process "good enough"? I don't think so.
I suspect we don't want to examine too closely what effect this has on the developing self. If we knew about it we might have to stop being in denial and face the truth. If you went to visit an abattoir you might find it hard not to become a vegetarian.
It is easier not to know. And even when we gain knowledge, so often it is used not to lead social change but to shame women.
I fully acknowledge I might be projecting my own neuroses on to others.
As a sensitive and cautious child, I hated being left with strangers. I still can't tolerate loud noise and crowds. (One of the worst experiences of my life was being left in the kids' club on an Italian cruise liner for three weeks when we emigrated to New Zealand. I swear those little thugs were mafia dons in training.)
Of course, not every one is like me. Maybe there are some children who are quite happy, or at least more compliant, about being brought up in daycare.
But as I have learned more about the science of attachment, I am not so sure anyone comes out of the industrial-scale childcare complex unscathed. There is a reason that communal child rearing on the kibbutz was discontinued.
A businessman in the childcare sector confessed over a glass of wine, that his business is like farming chickens. You have the free-range ones (infants cared for in the home) who are well treated. And then you have the caged ones, to maximise profits.
That little girl will give up protesting about going to daycare, because she has to. But doing so comes at a price. She learns to abandon herself and choose her parents' needs over her own.
Maybe parents can't hear what their children are telling them, or showing them, because it brings up too much guilt and painful feelings to be acknowledged. Maybe yoga pants mother does not see any other option. We need to find some other options. Our Prime Minister, Jacinda Ardern, has not put her new baby into a daycare centre.
And we can change as a society. It is no longer okay to hit kids, to conduct experiments without informed consent, to smoke inside, to send children to orphanages. And one day we will change in our approach to factory-farming daycare too.
I hope one day we will expand our psyches and become generous enough to give to our children something we never received. In the meantime I may have to walk a different route to class: like everyone, there are painful truths I can't bear to see.