Why Your Horse Ignores You on the Ground but Listens Under Saddle
The usual explanation involves respect. The more useful explanation involves clarity, consistency, and the fact that ridden aids are much harder to be vague with.
It is a common and genuinely confusing pattern. The same horse that is soft, responsive and attentive under saddle turns into something else entirely on the end of a lead rope: barging, drifting, stopping to look at things, generally treating the handler as scenery.
The explanation usually offered is that the horse does not respect you on the ground. That framing is popular and it is not very useful, because it does not tell you what to change.
Ridden aids are harder to be unclear with
Consider what actually happens under saddle. Your legs are in constant contact in the same place every time. Your seat is attached to the horse's back and communicates continuously whether you intend it to or not. The rein contact is consistent, and the aids are broadly the same on Tuesday as they were on Monday.
The horse has an unambiguous, repetitive signal set, delivered from a position it cannot ignore.
Now consider groundwork. You are somewhere beside the horse, at a distance that varies. Your body is at an angle that changes. The rope is sometimes loose and sometimes not. What you did to ask for something last time may not be quite what you did this time, because there is no saddle enforcing consistency on you.
The horse is not ignoring a clear signal. It is frequently responding accurately to an unclear one.
Under saddle the equipment keeps you consistent. On the ground, nothing does, and the horse experiences the difference.
Timing goes wrong more easily on the ground
The second factor is release, which is where most groundwork actually succeeds or fails.
A horse learns from the moment pressure stops, not from the pressure itself. Under saddle, releases tend to be reasonably prompt, because a rider feels the horse respond immediately through the seat and hands.
On the ground you are watching rather than feeling, and a half second delay is easy. That delay is not a small imprecision. It shifts which action the horse thinks was the correct one, because the release lands on whatever the horse happened to be doing when it arrived.
The consequences are different too
Under saddle, a horse that ignores a leg aid tends to meet a clear and immediate follow up. On the ground, a horse that drifts past a handler frequently meets nothing at all, because the handler is walking anyway and it did not seem worth stopping over.
Small non responses that produce no consequence become the default very quickly. Not through defiance, but because nothing has distinguished the correct answer from the ignored one.
What actually changes it
Decide what a request looks like before you make it, and make it the same way every time. Same position, same signal, same escalation if nothing happens.
Release the moment the horse tries, rather than when it completes. Rewarding the try is what produces lightness, and being late is what produces a horse that leans.
Ask for things that are achievable and notice when they happen. Groundwork that consists only of corrections gives the horse no information about what right looks like.
And treat consistent inattention that is new, rather than habitual, as worth a physical check. A horse that has changed how it responds may be answering a question about comfort rather than about training.