In every country there are unique species and living organisms that can be found nowhere else. Because of this, most countries have set up requirements in order to protect native species from diseases that might be carried by imported species from far away lands. Countries that have special or important agricultural aspects or history often have very strict rules.
New Zealand is one of the countries that strictly guards its native resources from outside threats with quarantines and other protective measures. Recently, the Ministry of Agriculture and Forestry (MAF) was forced to recall thousands of imported strawberry plant kits due to potential virus problems. The seeds may have contained viruses that could have significantly damaged the agricultural products due to their slipping through without being quarantined.
For the full story, see the article here: NZ Launches Biosecurity Probe After Imported Strawberry Seed Kits Avoid Quarantine
And, for more on what is required to send strawberry plants abroad, see this StrawberryPlants.org article: Shipping Strawberry Plants