There's a bit more nuance to it, in that you're not even allowed to buy at the official rate, and buying something in USD with a credit card gets you slapped with a 65% tax, so it's more like the 140-160 rate actually reflects the current real value of the currency. Having an 'official' rate nowadays is more of a performance to pretend that the already high inflation rate is actually a lot higher, and incredibly it works.