I would estimate that 15-20% of the patrons were children, of all ages.
Growing up, my dad loved to bet on the horses, and would go to Churchill Downs, occasionally accompanied by my mom. Going to the track involved Gambling, which was well known to be A Dangerous Adult Activity. There was never, ever any question of the kids accompanying them to the track.
So what do I make of today? I don't think that it's a function of, I am older than dirt. I would guess that this is an attitude unique to Lexington, KY, The Horse Capitol of the World. Keeneland has a special place in the heart of Lexington. It only runs 6 weeks a year. And a disproportionate number of local residents make some or all of their livelihood from the horse industry. Hence, hell yeah, bring the kids out to the track ?!?!?
Comments? Is there any other city in the US where parents would vaguely consider taking their kids to the racetrack to be a fine, respectable Sunday afternoon activity?