Good question TB. The Constitution's Article IV's statement about priveleges and immunities was interpreted by the SCOTUS in 1823 as embodying things we take for granted such as owning property and movement across state lines, not rights as we usually think of them. The Constitution's 14th amendment uses the same privileges and immunities wording to compel states to treat all of their citizens alike. It was understood to some extent at the time that the drafters of the 14th amendment meant the first 8 amendments of the Bill of Rights when they stated privileges and immunities in that amendment.

If you closely read the Bill of Rights you will see that almost all of them are restrictions upon government("Congress shall make no law ..."). Thus, they are not positive statements about what we as citizens can do (by the way, the Texas Constitution uses such positive statements).

TB, I think it all comes down to a matter of semantics. Although a drivers license is considered a privilege, what about voting? A couple of the US Constitution's amendments do contain language that refers to voting as a right, but there is nothing in the Constitution that otherwise defines it as such.

The Senate hearing was not a prosecutorial forum. Thus, it could be argued that the same interpretation of the 5th amendment that would prevail in a court did not prevail in the Senate forum. The privilege or right is not absolute as you pointed out about immunity.