Unless your company's interview process is
this,
this or
this, which I already know it isn't, then why should they pay a man more than R10k.
He is unproven, no experience (even if he had it means nothing from 99% of companies in SA), likely range from no technical expertise to programming wizard if you truly lucky. Even wizards are really horrible at everything else tho. You walk in and think you are the sh#t but really programming skill is pretty common. Look at the interview processes posted above: People think it is because those companies hire the best. Yes, sure but they also know that programming is a small part of the skills you need. So unless you are already a programming wizard, you'll just drool over yourself, sh#t your pants and quit a few months later because you couldn't cope.
Now you have a women coming in, she has very much the same variability in skill as the rest of the men. Some guys will tell you women suck but it is only because they think/(or are) programming wizards and somehow believe this makes them superior. In reality you skills are pretty common and what you bring to the table is easily replaceable and the reason you wouldn't get into above mentioned companies with your wizardry programming abilities alone.
What isn't easily replaceable is diversity which has been proven to increase the quality of output. Granted you can't hire a bunch of diverse muppets and hope that will do the trick. But since the casual "bank" interview is a muppet interview anyway, they are playing by luck and hoping to hit the jackpot.
So yes, there is a chance that your male friends earned less when they arrived. And women got more purely because they brought diversity to the table.
But the reality is that in highly competitive environments, which banks are not (I would know, I've been there), women aren't on equal footing.
They don't get promoted as easily and men shoot their ideas down simply because of their gender.
Whether you will ever see this for yourself I cannot say. So I would suggest you look on the internet. Where you'll find it is a big problem in the industry.
Else, you know, try interview with Google, Facebook, Twitter, Amazon or locally Takealot are using the same process. Get a job there, work for about 4 years and then we can discuss it over a braai.
EDIT: FYI I'm male.