The point being that they're temporary, not permanent. It's very unusual for them to be made permanent, with the exception of sexual abuse cases involving minors (or indeed any case involving minors). However, during a trial sometimes things are banned from publication until after a jury reaches a verdict to avoid polluting a jury.
Afterwards, the entire transcript will be published, and anybody who cares to can go down to the courthouse and read it. The cases you heard about were almost universally because the newspapers in question didn't want to have to wait.