It’s because Lions and Tigers do not co-exist in a shared territory anymore (thanks to humans).
However Tigers and Lions used to share common habitats in Asia, specially India and Iran before the end of 20th century. Fights between these two beasts were recorded in the accounts of travellers, folklore and stories.
20th Century had been the worst century for animals in these regions. Both British and Indian/Persian Royals hunted down Tigers and Lions in huge numbers, bounty was put on them and due to rapid urbanization and huge agricultural demands their habitats were run over by human occupation.
Lions were less of a shy animal compared to Tigers which preferred to hide in deep forests, so Lions were killed more, so much so that Lions went locally extinct in Iran and most of India.
Only 12 were left in a small forest in Gujarat, India by the end of 20th Century. They were able to survive because King of that region decided to protect them.
Tigers also perished as they were also hunted down to near extinction.
They became extinct in Iran and were only able to survive in small pockets of forests in India.
So, if not so for relentless hunting of Wild Animals by humans in 20th Century, Tigers and Lions would had still co-existed with each other in Jungles of Persia and India, and we may had witnessed Tigers and Lions fighting over territory and prey in the wild itself.
Credit : Quora
Picture Credit : Google