They are not “slow/dense/stubborn”. They are human.
People develop their behaviors for reasons. Once you understand how important those reasons are, it’s quite easy to understand why they behave the way they do.
I see a wide variety of people, from different backgrounds, male, female, gay, straight, religious, atheist, from different countries, different socioeconomic circumstances, and various ages and ethnicities.
One thing they all have in common is that they developed into the people they are today, because of their experiences in the early stages of their lives.
Many of these behaviors develop in order to survive in a particular environment, and are very effective adaptations. They often only become maladaptive when these children become adults, and these same behaviors no longer serve them well.
So the next time you have an issue with someone’s behavior, try using empathy first and try to understand why they might be behaving that way, before branding them “slow”, “dense”, or “stubborn”. It’s quite likely they aren’t too happy about it either, but changing deep rooted behavior isn’t easy to do.