In 1995, someone on an IETF mailing list pointed out that the HTTP "Referer" header was misspelled. Phillip Hallam-Baker, who'd proposed the field, cracked a joke about Daleks. Roy Fielding noted the Unix spell checker of the era wouldn't have caught either spelling. Everyone shrugged.
By then, software already expected the exact string. RFC 2068 marked it with [sic], the scholarly notation for "yes, we know." That was 1997.
Every HTTP request your browser sent today carried the same typo. Nobody chose to preserve the error. They just chose, repeatedly, not to pay the coordination cost of fixing it.