Sorry but I have to disagree here. The syntax of JSON is far simpler than XML or ASN.1, so a coder is more likely to get it right
The point is that it is possible to validate XML data as correct, using the document and its internally referenced DTD/ Schema. This is very different from simply saying that the document is well formed syntactically, which is, as you say, mostly straightforward.
There are solutions for validating JSON, but they are all applied after the fact and so XML does that the advantage of being better in this aspect.
I tend to use JSON for most stuff, and would generally reach for one of the binary formats (eg Avro) when a better type system is needed, but XML is still a good choice for things.
JSON is fine for what it is, but its not great.
There are well documented issues in the spec and how its implemented. For example, its straightforward to write a JSON doc, parse into memory and immediately output and see the resulting document be structurally different to the source. You don't get that with XML, Avro etc.
You could say "well, what doesn't matter", and you'd be right, until it does matter, at which point you're screwed.