(this text is present in RFC 7233 as well)

"A valid entity-tag can be distinguished from a valid HTTP-date by examining the first two characters for a DQUOTE."

Hm, no. If we want to properly handle weak etags, we either need to inspect three characters (actually position 0 and 2) for DQUOTE, or check pos 0 for DQUOTE or pos 1 for "/".

If we're not interested in weak etags, checking the first character is sufficient.