Why are there no tigers in Sri Lanka?

There are no wild tigers in Sri Lanka because the island kind of got cut off from the Indian mainland before tigers could even migrate, so it stayed isolated from their normal mainland Asia habitats. Because of that, the native apex predator here is the Sri Lankan leopard, not any tiger.

Tourists and locals, for reasons like old stories and a kind of casual naming, often mix up leopards and tigers. In Sinhala, the term "kotiya" was historically used for the leopard, but a lot of modern media ends up rendering it wrong, like “tiger”. And there’s also zero solid historical, fossil, or biological proof that tigers ever lived on the island. Tigers need huge ranges of dense forest plus grasslands, the sort of places that are currently only really found in places like India, Nepal, Bhutan, and parts of Southeast Asia. With no tigers around, the Sri Lankan leopard evolved into the island’s primary predator so it could roam more openly during daylight hours, unlike some leopards in Africa or India, where things can be different.