As the others mentioned, it’s closely linked with surf culture. Aussie surf culture has a big crossover with hippie and new age culture, with its inevitable links to
India. You see other names of Indian origin, like
Bodhi, popping up in surf families too. I wouldn’t be surprised if the Indian name
Jai is the origin of the Australian one.
https://nanowrimo.org/participants/christine-seaforth-finch
http://christineseaforthfinch.blogspot.com/