It was a tragic accident. One from which, unfortunately, the horse owner is unlikely to recover financially.
Sh*t happens sometimes, even when we've taken every precaution. Doesn't mean all horse use in public should be outlawed.
Our saddle club is invited to ride in a huge 4th of July parade every year. The liability goes to the parade organizers, the town, etc. Our insurance agent is also an attorney and rides in our club. (and has one of the worst behaved horses . . .)