Because frankly the public does not want to hear the truth.
George W. put a tentative, tepid toe in the water on this at the beginning of his second term. He got his head handed to him.
Politicians won’t try THAT again.
The cap on payroll tax is going away IMHO. And a Tobin Tax will be implemented to help fund Social Security. The only fixes that are politically palatable to most voters IMHO.
This is why the FedGov has been trying to legalize illegals - they want their wage withholdings to replace the 40 million (otherwise SS paying) Americans we have sacrificed to abortion.