I was reading The Fig: Botany, Horticulture, and Breeding and on page 133 I found this:

Different fig cultivars can set fruit with or without pollination. A
consistent difference in nitrate levels has been detected in persistent
versus nonpersistent fig cultivars (Crane 1986). The average nitrate con-
tent of persistent figs is triple that of nonpersistent ones during Stages I
and II of summer main crop figs. By Stage III nitrate is not found in non
persistent fruit. Crane (1986) showed that indoleacetic acid (IAA) is
inhibited as nitrate levels rise and suggested that the reason nitrate levels
differ so greatly in persistent versus nonpersistent figs has to do with the
regulation of indoleacetic acid oxidase. Therefore, persistent cultivars
are expected to have higher auxin levels. Indeeed, auxin application was
found to stimulate fruit set in nonpersistent Smyrna-type figs (Crane and
Overbeek 1965; Crane 1986). Various applied growth regulators, includ-
ing auxins, gibberellins, and cytokinins can induce persistence in the
Smyrna-type 'Calimyrna' cultivar (Crane 1986). The maturation process
of auxin-induced persistent fruits is somewhat longer than that of cap-
rifled ones, but their morphology is similar.

My guess is that you would need a syringe to inject the substance into the fig flower...

I am not an expert on this, I prefer the "common" figs,
aka., no capfification needed to set fruit. But...
here is an intesting experiment done by Chis DiPaola of
(of now-closed Belleclare nursery; NY) on one of his figs
(the spray [due a pevious descussion] is presumed to have contained some gibberellins [acid]):

#100 Perkounis-Large purple/black, red center from island of Mykonos. Grows well in hot climates.
Originally a Class II San Pedro Type, producing large brebas only. Main crop was only
females so none of the figs would develop. After experimenting with growth stimulant
sprays containing a hormone to inducing specialty flower to become large for exhibition,
Belleclare sprayed this into the eye of the female fig at halfway point of 28 day cycle and
seven days later. As a result, a main crop was produced because the spray mimicked the
male hormones. This occurred several years in a row and then Bellclare stopped for three
years in a row and during that time, the tree adapted and produces self-fertile main crops.
The hormone spray came from edible Landscaping, Afton, Virginia.

That's interesting, what's confusing is how did the tree in the experiment adapt after 3 years and became self fertile. I doubt that a spray will change the genetics of the entire tree, just by spraying something into the eye of the figs.
My guess is that the tree was a common fig, but dropped figs while young, so they thought it was a smyrna. They should have attempted that with a known smyrna type like the Calimyrna fig.
That's my guess.

If this works, then the commercial growers will save money with labor by applying the spray with commercial sprayers instead of having workers hang male figs on the trees.

Thanks Gorgi for adding the extra information.

Bass: We should also take into consideration that last part in the text :
The maturation process of auxin-induced persistent fruits is somewhat longer than that of cap-rifled ones, but their morphology is similar.

I think in commercial fig orchards the objective is to have the fruits ready as fast as possible. Also, I was advised that the earlier in the season the figs are available the higher the price due to the fact that there are less figs available on the market.  
 
To this, in countries such as Turkey the cost of labour is cheap and the usage of auxin in large quantities in orchards that span on hundreds of hectares would certainly add extra costs to the production.