It's precisely the kind of thing I would not want to figure out by hand, but it's fairly easy to validate that it does what I want it to. The use case here is well defined, and it's pretty easy to write tests for the expected behaviors. In general, I like to treat tests as contracts for the functionality of the app.

Meanwhile, the same argument would apply to hand written regex as well. People write code that works on a happy path, but breaks in some corner case all the time. This is a common occurrence without LLMs.