If a horse decides not to be tied,
eventually something will break, either the rope, snap, item they are tied
to, or the horses neck.
Training is the answer in 99.5%
of the cases, but I would not take an unbreakable halter and lead and leave
them tied for days in order to teach a horse to tie unless this is a horse
you would rather have dead then loose. Some horses have a panic button
they cannot overcome.