Sven is basically right. The feature is a matter of style rather than grammar. It is associated with comparison of the forms:-
X visits her doctor more often than does Y.
X runs as fast as does Y.
The general norm is that noun subjects come before their verbs except in a question (or a second person imperative.
The exception can also occur in some other contexts, usually (possibly always) with intransitive verbs.
Onto the stage to loud applause strode the great conjurer.
What is the point of these deviations from the norm?
First, they occur in contexts where the meaning cannot be doubted. Second they generally involve intransitive verbs. There might be exceptions or at least room for reasonable disagreement about cases like this.
With the uttermost scorn refuted the witness the famous barrister (or vice versa!)
We can probably agree what is being said, but not without some head-scratching, even if momentary. Only fully inflected languages can get away with this.
The point of the device is emphasis. In any sentence, the strongest positions are (often/usually) the beginning and the end; in addition, taking a word away from its expected position draws attention to it, provided it is grammatically possible.
In your examples we have comparison between two things. What could be a stronger reason for putting the two nouns at opposite ends of the sentence?
a.The Internet allows more direct and open communication than does the real world.
b.I have a worse temper than he does.
c.These days Iran is no more inclined to welcome outsiders than is Nigeria or Venezuela.
d.He is more interested in video games than his girl friend is.
In a and b the word ‘does’ is dead: it is a pointer to the verb. (Incidentally, since the main verb is only ‘have’ I think it would be better to repeat ‘has’, enhancing the balance.). In b, it does not make much difference which way round you put subject and verb. You could write “...than does he”, but nothing is gained.
b2. The King was more likely to have people put to death than was the Archbishop of Canterbury.
The comparison is fuller and more substantial. So the reversal has clear point.
c. places the object of comparison at opposite ends of the sentence, so making it a ‘physical’ contrast and so more striking.
d. You could do the reversal, but there is no particular point.
Deviation from norms is a recognised stylistic device. The point is emphasis by using the unexpected. Those you are asking about have become more-or-less standard.
Compare these with great literature.
- Tomorrow and tomorrow and tomorrow
creeps in this petty pace from day to day.
[Macbeth on learning of Lady Macbeth’s death]
There is huge weight on the adverbs by putting them at opposite ends of the clause, from the repetitions and from the syncopation of the iambic rhythm, slowing it down and making the line limp along at a “petty pace”. And “petty pace” ‘creeps in’ late ( after the verb “creeps” of which it is subject.) and the more noticeable for that. Of course, Shakespeare did not think it out like that. It just felt and sounded right. That is what literary genius is like.