They have been. Catholic excommunication can take two forms: "ferendae sententiae" which is incurred only when imposed by a legitimate superior or declared as the sentence of an ecclesiastical court) and "latae sententiae" which automatically incurred at the moment of committing the offense for which canon law imposes that penalty. Biden, Pelosi, Kennedy and many, many other public and private "Catholics" have excommunicated themselves. The pity is that they are not already widely recognized and acknowledged as excommunicated Catholics.
Note that excommunication is not intended to be a punishment, but rather a medicinal penalty whose purpose is to encourage sinners to repent. The final judgment and Salvation are reserved only to God.
Peace be with you.
In his own diocese, Biden has been excommunicated. It has to happen in the diocese in which they live.