.... to vote, which is really their constitutional right, then that State has the  responsibility to make sure it issues that ID to everyone without any expense on the part of citizens.    They should be able to walk in to a State agency and get that ID and those who are disabled and cannot physically make it, the State agency has to go to their houses of those people and process their ID.

That is done even in a less developed country like India where enumerators go door to door to register voters.

For Secretary Hillary Clinton, if you don't know she is a former First Lady and has Secret Service protection.    It is Secret Service that will require an ID and also there will be metal detectors and restrictions on taking fluids like bottled water etc.,

If you don't want to go through the security check, then no one is forcing you to go.