I think a lower amount of training data for Haskell might be a reason.

For core system functionality maybe. But for most applications Rust slow compiler iteration speed becomes a bottleneck when the likes of TypeScript (with Bun) and Go have sub second iteration times.

Plus AI is also good at catching, in other languages, errors that Rust tooling enforces. Like race conditions, use after free, buffer overflows, lifetimes, etc.

So maybe AI will become to ultimate "rust checker" for any language.

The way Haskell handles memory is weird and can be unpredictable.