It is quite strange that you are comparing a biosecurity threat to a fairy tale. There is actual scientific evidence of a pathogen that eliminated a banana type and caused massive economic loss, and you pretend that there isn't. We have biosecurity alerts regularly and some times quarantine procedures fail, e.g. http://www.outbreak.gov.au/current-responses-to-outbreaks/wh....
It is the same sort of self serving delusion that leads to climate change denialism.