Incompetence.
They should be screening anyone who is from or visited any of the countries with more than 100 cases.
They should asking all passengers of all flights if they have any symptoms. And to report any symptoms over the next 14 days.
They should follow up with anyone who has symptoms. And if they have the virus, they should contact everyone on the flight.
BREAKING: Italy reports 166 new cases of coronavirus and 4 new deaths, raising total to 821 cases and 21 deaths
https://twitter.com/BNODesk/status/1233451529031634947