Obvious examples are a pair of scissors, a pair of gloves, a pair
of bookends, etc; they never come singly. Or, if you are describing
two individuals who are similar or are in some way associated with
each other: a pair of liars, a pair of seal pups.
I therefore don't see why two tickets should be turned into an
inseparable pair, suggesting that one on its own would be useless,
which is silly.
He's contradicting himself here.
The two tickets he is referring to are indeed 'similar or are in
some way associated with each other', aren't they? They look
similar, they feel similar, they're from a similar source and
they're for a similar purpose. Two liars are similar, and two seal
pups are similar, why can't two tickets be similar?
Moving on to the next paragraph, don't tell me that if you separate
'a pair of liars' or 'a pair of seal pups', they each become
useless. I honestly didn't know that liars and sea lions can only
exist in pairs and not on their own. So following the writer's
reasoning, a person can never lie on his own, for it would be
useless and silly. 
