I think "the standard" is a bit too strong of a statement.
You're over thinking it :)
Package names are supposed to be capitalized, so yes CamelCase is something generally expected,
Also know as the standard convention
but as for method names I don't see how camelCase is better than CamelCase, both are used, although snake_case is something I see much more often in Perl code.
Do more research :)
You see one used more than the other, so one is the standard camelCase