I'm a slow learner regarding chickens, I feel like most people who have had them for nearly three years like me know a lot more than I do, and are able to handle and care for them better than I am. I'm very attached to our two roosters, but Théo is still showing signs of agression with us, and I know that my partner would rather not keep the two of them, especially if they start to fight. It's his family's place so he'll have the last word if I can't find a way to convince him.
I think you are overestimating others and underestimating yourself.
Getting familier enough with chickens to handle them easily is very much a double edged sword. Fundamentally chickens don't like it. This is the normal. I know people say my hen loves cuddles etc, but that isn't the normal for chickens. There are studies using thermal imaging that show how much it stresses the chicken. With the allotment crew after a year of two to three hours a day spent with them I can catch most of them now. 3 are particulalry difficult. They still don't like it, not even Lima.
Roosters in my experience are a bit like dogs; they tend to fare best with just one person doing the training, feeding etc. Humans are not the great communicators we would have ourselves believe. Our understanding is highly limited to our own species.
There are lots of posts on BYC where other people who are not seen by the chickens as part of the tribe get attacked or run into other behaviour problems.
Voice tone, relaxed mindfull movement and confidence are key to managing all other species. Other creatures are very good at picking up that "I'm cool and not trying to harm you vibe." They are also very good at picking up, this one is scared, vunerable, sick, dangerous etc.
It all takes time, lots of time and not just the passing of the hours. time actively involved with the chickens.
The anecdotal evidence I have suggests I'm wrong in that I beleive a human that handles their chickens reduces predator awareness.

An added problem with roosters and sometimes hens is that once you start handling them you become their best friend. I've had many months of best friend roosters and some of their habits can need a degree of understanding that some may find a bit of a stretch.
I still struggle everyday with some chicken issue and learn something about the chickens everyday. Most of the time one doesn't know one is learning until a point comes where through watching and then noticing a repeat, one starts properly observes rather than watch. I find I often know the answer to a particular problem but cant take the necessary action. Sometime it's I don't have the kit or the drug. At the allotments not having a place to examine and confine is a constant frustration. Not having the time is another. The more chickens one has the more time is needed to do the routine checks, even if they are random spot checks. Not having the money for vet care is another.
Tonight I tried to get a worming dose down the sick legbar. I didn't manage it, or at least not the full dose. I may have to tube it in but of course, I no longer have a tube feeding kit.
Finally much of the advice one reads is a reapeat of something someone has read. Sometimes if the person shows where they get the advice from as casportpony sometimes does and links to a reference when it comes to dosages, that's helpfull.