Honestly the only certainty is that unless you have been 100 percent responsible for a very young child for more a few days, you have no idea what you are talking about. I don't mean that directed at you. Just my own generalisation based own experience and the opinion of every other parent I know.
Life as a parent is completely different than life before.
I saw a woman completely lose her shit in a museum with her kid. Before I became a parent I would have judged. But when it happened I just thought "poor woman, I know how it feels, just giving it her all and she's got nothing left to give right now, how many times have I felt like that, how many times have I failed to live up to my own ideals as a parent".
I'm beyond fortunate that she's fully into being a mother, calm, patient but knows where the boundaries are. And that's reflected into our kid. He's so incredibly easy to parent, it's insane.
I look at his friends - all good kids. Boisterous, outgoing, a bit wild and uncontrollable, but fundamentally good kids. They fight with their siblings, and they're learning how to navigate the world.
And then I go shopping. We live in lower socio-econimic area, and it's genuinely just saddening to see what goes on. The number of parents that are actively, in public, swearing out their kids and just having the kids stand there quietly shrinking away is heartbreaking.
I don't know what's going on in the parent's lives, and I know being a parent is immensely difficut, and none of us are equipped from the outset to really become one... but yelling at your kid for being a f*ck in the middle of a shopping center? I fail to see how any of that is OK because of 'circumstances'. At some point you have to grow up and be an adult. You put this kid here. You need to take responsibility. It doesn't mean it's easy, but if you can't self reflect enough to know that's not OK, then you're a big part of the reason the kid is how they are.