Popular "proof of onward travel" services used by thousands of budget travelers and digital nomads are facing criticism after a South African traveler lost thousands of dollars discovering a critical flaw: the services exclusively book through United Airlines routes requiring US transit visas—information not disclosed on their websites.The traveler, heading to Belize, purchased reservations from both OnwardTicket and DummyTicket to satisfy the country's requirement for proof of departure. Immigration officials in Belize City rejected all three bookings after a four-hour customs ordeal, because South African passport holders need US transit visas for United Airlines flights—even for brief connections."OnwardTicket and DummyTicket will book you through United Airlines exclusively," the traveler warned on Reddit. "A UA flight is guaranteed to layover in the USA, and therefore the only way these websites work is if you are either a US Resident or have a Transit Visa."The issue affects travelers from dozens of countries that require US transit visas, including South Africa, many African nations, parts of Asia, and Latin America. Neither OnwardTicket nor DummyTicket prominently disclose their exclusive use of United Airlines, leaving travelers to discover the problem only when immigration officials verify the bookings.When the traveler contacted DummyTicket requesting a Copa Airlines route instead (which doesn't require US transit), they were told the service only books United Airlines flights. DummyTicket promised a refund but had not delivered 40 hours later, according to the traveler's account. OnwardTicket couldn't be reached for comment.The traveler's journey had already been complicated by an earlier issue in Colombia, where they discovered that splitting bookings with separate tickets starting and ending in the same country is illegal, forcing them to rebook through Brazil instead. Combined with the Belize ordeal, the trip cost an additional ZAR 32,000 (approximately $1,700 USD) in replacement tickets and accommodations.For travelers heading to specifically, the Reddit post offers a workaround: through their option, which can be used for immigration purposes. The reservation lasts long enough to clear customs, and if not confirmed, it simply expires.Digital nomad communities are calling for these services to clearly disclose routing and transit visa requirements upfront. While OnwardTicket and DummyTicket market themselves as universal solutions for visa-free travel, they appear to work reliably only for US passport holders and those with US visas—a significant portion of their customer base who would have less need for such services.Travelers from non-US countries should verify transit visa requirements for any route booked through these services, or use airline-provided reservation holds when available. The alternative—discovering the problem at immigration—can derail entire trips and cost thousands in emergency rebookings.