That _shouldn't_ be ambiguous, `false` is a valid JSON document according to specification, but not all parsers are compliant.

There's some interesting examples of ambiguities here: https://seriot.ch/projects/parsing_json.html

Trailing commas, comments, duplicate key names, for a few examples.

Trailing commas and comments are plainly not standard JSON under any definition. There are standards that include them which extend JSON, sure, but I'm not aware of any JSON library that emits this kind of stuff by default.

I'm not aware of any CSV library that doesn't follow RFC4180 by default, and yet... this whole thread.