The safety plan for 2021 Worlds *does* include testing upon arrival of skaters and officials.
What are the health and safety measures in place to protect the Skaters and Officials at the event?
... Among several safety measures, Covid-19 tests are mandatory before arrival, upon arrival and during the Championships week as well as a daily health screening.
A difference between U.S. Nats and Worlds seems to be the requirements for the limited number of
media attending in person.
The
media at Worlds will not officially be part of the bubble. For example, they not will be staying at the official hotel, which is right next to the arena. (Is it possible that the official hotel is not large enough to have room for media? Non-local media are given the choice of two other hotels.)
Whereas at Skate America and U.S. Nats, the few media on site were officially part of the bubble, and needed to meet all the requirements of the bubble -- including staying at the official hotel, adjacent to the arena.