The Hyperinflation has many causes. One major one is Counterfeiting. The Hylian government did nothing to stop it, and it got worse in the late 1970s when 90 percent of Rupees were made in China.
Inflation rates began to rise in 1981, where the Red 1 Rupee, became worthless. The next month, Hyrule created the the Orange 50 Rupee. Instantly, the mass printing of it in China made it worthless. By the January of 1982, it took 30,000 Rupees to be one USD.
Hyrule stopped making the old versions, and created a silver 50,000,000, Gold 5,000,000,000 Rupee, and an Azure 9,001,000,000. By July of that year, Hyrule stopped making those and created the Miltrupee (Million Trillion Rupee). It was worth 1,000,000,000,000,000,000 Rupees and 5 U.S. cents. The introduction of the Miltrupee further spiked the inflation rate, and by this time prices doubled every week.
The inflation rate began to further rise when Hyrule was hit with war in the 90s, and by 2011 a jar of milk costed 11.8 million trillion trillion Miltrupees. Today, prices double every 8 seconds, and there is no sign of to end of hyperinflation.
Compared to other countries, this problem is one of the easiest to solve. All King Harkinian must do is get rid of the Rupee. It is unknown why such has not been done.