I always read gottatrot's post in the light of letting your horse discuss your every decision. I went back and read them again, and still get that vibe due to her responses to my posts. It could be I am still reading them wrong, and it was not the intent of the post to make me feel as if I should not own a horse.
I wasn't sure why you took the machine/motorcycle comment to mean yourself personally, I still feel anyone (not anyone in particular who has posted) who has no room in their thinking beyond a blind response to a cue from a horse does not have the compassion to ride a living, breathing creature. That's because I've ridden a few of these horses that will respond "no matter what" and their personality has been shut down while they have a deeply rooted anxiety about expressing an opinion to the rider.
If a horse discussed every decision with a rider, we could not ride them. Horses are agreeable, and after they learn cues they mostly agree with what we are asking. However, I believe we ask a question and the horse answers. Will you turn right? Yes I will. Will you back up? Yes I will. Sometimes the horse says no. Then you can either figure out why the horse says no (does he understand the cue? am I asking in a different way than I usually do? have I missed the fact that I'm asking him to back into a giant hole?) or you can just try to force the horse to obey right now. If you know the horse, you can use your brain to decide quickly what is going on. You might know he's questioning if you're going to make him do it, so you might cue again. If the horse always agrees with you, you should see what makes this time different. That is what a horseman would do.
I have ridden horses trained by people who believe horses should be "yes" men and I've ridden with people like this. They have no tact and do not listen to their horses. The horses often suffer because they will comply until they are absolutely unable to, and if that makes the situation turn bad the horse is abandoned or put down.
But I've also ridden with people who equate the amount or type of training with how compliant a horse is. Which I believe is another fallacy because there are highly trained horses that are brilliant, stubborn, and often non-compliant. There are also horses with very little training that are willing, sweet and will try to do anything and everything they are asked to do. These horses can appear as if they've had lots of training, because they try so hard to figure out what is being asked and will fill in any missing details.
Now many people say this or that type of horse is one they like to ride, and this or that type of horse is one they would avoid. That is fine, but if a certain type of horse will turn away from a nest of bees when asked or head into a spooky patch of ground just because they have been trained well and are agreeable types, that doesn't mean all well trained horses would do so.
That is my main issue...because of the people I meet in the real world who believe so strongly in the idea that training and leadership will turn any horse into an obedient child who will override his instincts when asked and comply. Which as Smilie said, past experiences and training will affect the horse's responses, and from what I've learned of horses, so will the innate ability of the horse to control their emotions and physical responses to fear versus going into a more instinctual state.
And why I have an issue with this is that multiple good horses are discarded and people think there is something at fault with the horse. The horse may not be right for that person, but the horse gets a label that often follows throughout an area. I've seen horses at barns where I've been that have been put down because one person thought the horse should have been trained better and the horse behaved on instinct.
I've seen many more horses sold on, but more often I've seen the horse just sit, abandoned while the owner no longer provides the vet care and good diet they did prior to losing faith in the horse. Plus it often takes quite some time as people spread the word the horse is "crazy" or "unridable" before someone actually tries the horse out and finds that the horse is sound of mind and well trained, but the owner had no room in their mind for the horse to behave like a prey animal and react on instinct.
Again, not saying this is what I'm hearing from people posting here and now. But as to why I believe horses are not going to behave like machines, and why I agree with Smilie that any horse can "lose it" sometimes. I've also read that more people are injured by well trained and mellow horses than are injured by horses with less training that are perceived as more dangerous. I believe that is because many people believe too much in a horse's training and are less careful than they would be with a less well trained or hot blooded horse.