Your confusion is understandable, and the writer of any grammar book who calls 'go' in a sentence such as
It is vital that she go to bed early.
a 'bare infinitive' ought to be shot!
'Go' is here, as a previous contributor has commented, a form of the subjunctive mood, NOT an infinitive of any kind (bare or otherwise).
However, to return to your original question: in contrast with expressions such as 'It is vital/essential/important that...', the subjunctive after 'It is unfair that...' is, I would say - while not inconceivable - relatively uncommon. Either the indicative or the should-form would be the normal constructions, the former where the event or condition referred to is openly admitted as a fact, and the latter where it is simply conceived of as a possibility.
Thus,
It is unfair that nonresidents are not allowed to vote.
(that they cannot do so is an undisputed fact).
or
It is unfair that Peter should be paid more than Paul for doing the same job.
(more likely in a situation where this is not actually happening, but merely a proposal or theoretical possibility).