Maybe both parents had to work two jobs. Maybe they had their own life challenges.
Perfect parenting, if such a thing exists, certainly has an economic minimum price.
And likely has a previous generation upraising requirement as well. There's a reason maladaptive cycles continuing down through generations happens: parents are often defined by their parents ad infinitum.
What matters as a parent is being the best you can be, and striving to be better than your parents were.
All that matters is the outcome. The child has to live with it.
Offspring repeat maladaptive traits which were considered normal or effective. Any skills lacked will have to be self-taught or sought out once they become aware. The narrative of being the best we can be and putting in 100% effort as parents unfortunately only makes us feel better about our situation/security, personal life choices (including avoidance), and quality of connection. Many people have kids for the sake of it and to improve their own lives. This is one of the insidious roots of a potentially painful upbringing.
Shifting the thought framing to seeking "reasons" rather than "blame" for behaviors allowed me to see failures or betrayals for what they are. I could then grieve the times I was hurt despite the love and intentions. I processed anger and bitterness about this along with a host of unresolved traumas and associated emotions that I never had the chance to resolve internally at the time. What remains is a dull universal sadness at seeing the truth of all this - the obvious harms we are doing to ourselves and each other despite "best intentions". It's a small price to pay to finally be arriving at a sense of internal peace.
Effective or "good enough" parenting requires a range of skills including emotional intelligence and awareness of our flaws in order to reduce harm, and to treat the child as a separate individual. Everyone gets stressed and makes mistakes, but those skills determine whether it's an opportunity to teach children how to self-regulate and resolve conflict, or an internal clusterfuck that sets them up for a lifetime of interpersonal issues, poor self-regulation, and disappointment. Prioritizing emotional presence is critical.
Some people with deeper issues can cause problematic child development and attachment regardless of material conditions or physical presence. It's mainly whether the child has room to grow themselves or if they are stunted/controlled by the environment.
I believe we should look at ourselves deeply and honestly to work on our own state of mind before diving into commitments. The reward of internal peace is worth the price of realizing this reality. From here we can improve it for the next generations.
That's just your own projection. Both sides adapt, and you haven't heard the other side yet.
Since children turn into adults, and not the other way around, I'd say that children adapt much more than parents.