How much of screaming kids, is bad parenting? None of the kids in dual working parent, or single parent households that I grew up with, screamed.
Yeah because each kid is different? Kids are not factory products that you can just quality control. Germany even has a law specifically allowing kid noises[0].
[0]: https://www.theguardian.com/world/2010/aug/16/germany-childr...
Probably not much.