TB's at the track have seen, and know, quite a bit: But, they know it in a very controlled context, and, that context revolves wholly around them.
There are few variables to the track routine, and everyone involved knows the rules.
I've all too often seen the unhappy results from humans who presume that
any OTTB who has raced past a packed and noisy grandstand, totally focused, at speed, enroute to the finish line should inherently possess the slightest clue about uneducated and unrestrained vehicle traffic on a public road, or immediately figure out and enjoy a leisurely trail ride, at a walk, on unmaintained surfaces, whether solo or in dubious equine company.
Most American TB's have no experience with being ridden out, over roads or trails, when being started prior to beginning their racing careers. Some few do, and that is truly wonderful. I think it helps promote a thinking and ratable horse.
Nonetheless, to start OTTBs' riding out, it's easiest and quickest to begin acclimating the OTTB to going down the road if one can employ an unflappable tour guide: The OTTB is already used to a pony horse. We are very grateful to a neighbor with just such a dear quarter horse mare who imparts her experience, wisdom and confidence to the green or unsure TB.
This is a process: It takes as long as it takes.
Some TB's NEVER really care for the world outside; they view it as a scary punishment rather than as a relaxing reward. If so, then we don't go there. Yet, those same TBs can still excel as stellar performers in the arena.
Melodee, http://www.chezchevaux.org