I definitely become an authoritarian when my kids have pushed me beyond the limits of my patience. Your example drops an unaware adult into a child's position in this scenario. A more realistic view is that each parent/child relationship is full of give and take, and the relationship adapts over time. Excellence is a habit and parenting is no different. To do it well you need to focus on building a relationship of trust and respect that flows both ways.

I think what you describe as bad parenting is largely due to parents struggling in their own lives and this negatively impacts their relationship with their kids. Many also just don't seem to think very deeply about how they can do a better job. The causes are manifold but can be summarized into a few broad categories: insufficient resources to raise a child (time and money), insufficient support network, poor physical or mental well-being of the parents, etc. Having kids too young compounds these problems.

Of course these are probably the right reasons for bad parenting, but it's bad parenting nevertheless.

About patience, I like this quote: “if you have to tell a child something a thousand times, perhaps it is not the child who is the slow learner.” - Walter Barbe