Things that don't make sense

Several years ago, I had trouble with
my foot. It turn out to be a spur on the
bottom.. So they prescribed a med for me.

At the time I was employed and had health
insurance. And a co-payment prescription deal.

When I went to get the meds, I couldn't find
my card. And I don't have to use prescriptions,
so there was no recorded at the pharmacy.
So I told her to go ahead and fill it... after all
how much could it cost? $15 for the 20 pills?

Well, she brought it over and said that will be
$48!!!!!!... I told her wait a minute.. let me see if
I can find my card. I dumped all of my stuff out
of my wallet and in the shuffle of cards, where it
was. So she redid the billing. It cost me my
co-payment of $9.00.

What blew me away was the fact it showed
on the bill.. That the med cost $28 and with
the co-payment I paid $9.

So if you pay in cash, you pay $20 more,
than the insurance company is charged.
Excuse me.. but will some one explain
that one to me? I don't get it.