From the story linked in the one quoted beatofhawaii.com/why-these-hawaii-travelers-were-jailed-and-deported/;
Charlotte Pohl, 19, and Maria Lepere, 18, arrived in Honolulu from Auckland with plans to explore Hawaii before continuing to California and Costa Rica. However, their flexible travel style — including a lack of pre-booked lodging for their planned five-week Hawaii stay — raised red flags for U.S. Customs and Border Protection (CBP).
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The ESTA (Electronic System for Travel Authorization) allows citizens of certain countries to travel to the U.S. for short stays without a visa. However, ESTA approval permits travel to a U.S. port of entry, where border officials have the final say on whether to grant entry.
In many cases, travelers without clear lodging plans, a well-defined itinerary, or proof of sufficient funds may be denied entry. U.S. officials may also raise concerns if they suspect a visitor could be planning to work illegally or stay beyond their permitted time. Even honest answers about working remotely or being flexible with travel plans can raise additional questions that may not end well for some visitors.
In this case, the travelers said their spontaneous, flexible travel style — common in places like New Zealand and Thailand — did not translate well when entering the U.S., where stricter documentation is often expected.
Germany’s updated travel advisory now explicitly warns that “entry to the United States is at the sole discretion of U.S. border authorities.”