OK why is it that I can lead my horse past a tractor with its engine running, and he trusts me to do it, but if I was on him he would leg it? Is it the "wolves will get you first" when you are on the ground, but "me first" when Im on board?
My spooky mare is like that- terrible on her own, but really confident if she is following OH on his bike. I am convinced it is because she thinks the little metal pony will get eaten first!
My daughter's horse is like that. We've decided that he feels she is in charge when she's on the ground but it is up to him to keep them safe when she's riding.
He has saved her from plastic bags, small ponies, suspicious lawn chair and various difficult to see gremlins so he's definitely doing his job.
If my boy gets scared then I lead him past whatever has scared him and he will follow me anywhere. I don't have his full trust when ridden which on one level disappoints me, but on another level pleases me that he will trust me to lead past anything. They are complicated animals and what ever works for the individual horse/pony is right.
I have spent years jumping off to lead my girl past things. It's as though she thinks she's on her own and forgets I'm there, then breathes a sigh of relief when she realises I haven't abandoned her!