It only works in Rust if you have code that is parallel-without-concurrency.

Databases and operating systems are inherently concurrent. They deal with concurrency sources outside the process running the Rust code. Because of this, they don't get the magical shared-xor-mutable => deterministic-concurrency benefit that Rust is famous for.

And, frankly, if you tried to make SQL/ACID shared-xor-mutable you'd completely cripple it. Databases are inherently concurrent.