Tired or not its simply bad parenting. I was raised like this and it lead to many behaviours that needed forcible correcting later in life as well.
Being somehow born significantly smarter than my parents this caused an incomprehensible amount of conflict because my parents were raised both in extremely strict Christian european households, they would take out their anger on me, I have distinct memories of sometimes driving home from a restaurant even at age 10 and my parents would tell me that my behaviour was bad and that they were going to hit me when we got home and I would spend the entire car ride terrified trying to reason my way out of it, they almost never provided good reasoning or explained how to better myself, but when we got out of the car and were in the privacy of our own home sure enough, they would take out their frustrations on me for 'embarrassing them' and would hit me until they ran out of energy, this was considered normal.
As the years past things like this got worse, european families would often sit around and virtually circle jerk each other on these things, a family friend once bragged "My father would hit you once across the face, and if you asked why, he would hit you a second time for questioning it" another retorted "yes and look how we all turned out, the problem with kids these days is that there isn't enough discipline" these were misguided adults, they didn't believe in talking to your kids and teaching them better, they just believed in a cycle of hitting your kids until they were too afraid to step out of line, this heavily impeded me throughout early adulthood, I came to realise I was afraid of trying new things, speaking up, being the centre of attention, I also struggled with morality and violence for many years because I grew up in an environment where, if you were strong enough, you could boss others around violently.
If you don't have the energy to be a parent, don't have a kid, having a kid shouldn't be what people consider the default, I certainly don't think kids are for everyone and there are many parents out there who simply shouldn't be parents.