They mention https://pola.rs/ and highlight how it has the exact same properties (out of core etc) but don't include it in benchmarks and no mention on their detailed comparison page.
It's because they are comparing to distributed solutions only. Polars is one of the fastest solution for single computer workflow, but it doesn't support distributed workflow.
Hello! Daft developer here - we don’t directly use Polars as an execution engine, but parts of the codebase (e.g. the expressions API) are heavily influenced by Polars code and hence you may see references to Polars in those sections.
We do have a dependency on the Arrow2 crate like Polars does, but that has been deprecated recently so both projects are having to deal with that right now.
I don't see any direct dependencies to polars. But in the comment, they wrote that some part are "taken from", "influenced by", "adapted from" and "based on" polars.