WHAT IS THE REAL DEAL WITH COVID TESTS?

The Bahamas has now switched to PCR tests as the requirement to enter our country, including citizens on the country.  Still seems a bit strange that you can exclude a citizen from his own country because he has gotten a disease but no one wants to put up a fight.  The casualty of the virus attack is civil liberties.  Those who are concerned about it are  dismissed as irritants.  Here’s the thing though.  On CNN there was Anthony Fauci, the medical expert from the US, saying if we read him correctly that the antigen test is the best test for determining whether you are infectious or not.  The PCR simply confirms whether you have the virus or not.  You can continue to have the virus for months but not be infectious.  The question, we now raise is why then are we switching to the PCR test if the test is useless when it comes to determining whether or not you can spread the infection?  Just asking for a friend.