How can they do this!??!

So while vacationing in Cozumel, Mexico, I came across the Coke machine pictured here.  What I want to know is how Mexico can charge $7.00 for a can of Coke.  And we're not talking Mexican money - we're talking $7 in U.S.  

Now I understand Mexico isn't as well off as us, but this gives them NO right to cheat us out of a can of coke.  I can understand charging that amount for a margarita... but not for a soft drink we can purchase for $.99 on the corner here.