In economic terms, the market for allotments is in disequilibrium because the government has effectively set a price floor for the allotments.
In recent years, the demand for allotments has gone up. At the same time, the supply of allotments has remained steady or has even dropped due to the fact that land is very scarce and local governments have sometimes needed to sell allotment land. If this market were allowed to adapt on its own, a rise in demand and a steady or decreasing supply would lead to increases in prices. The market would then be in equilibrium.
But the local governments do not allow prices to rise as they (economically speaking) should. The governments do not want to raise prices because doing so would look bad politically. Therefore, they maintain what is, in essence, a price floor, leading to a shortage in the market.