And Morons out breed tigers 1000000 to 1.
Millions of people probably walked by that enclosure and saw the tiger safely.
The boys were attacked because at least one went over the barrier and they teased the tiger. It was likely able to escape the enclosure before, just didn’t because it was fairly content and the enclosure was the tiger’s territory. The tiger was young, healthy, athletic, and they invaded its territory and made it angry enough to get radical on them.