Bus and driving school vehicles are charged with gas, that is, the units of these vehicles have already paid the money to the gas filling station, so when the gas is not enough, they must be satisfied first. Moreover, when there is a shortage of gas, the gas at the filling station is only residual gas, and not many cars can be added.
The shortage of upstream resources and the rapid growth of downstream demand are the fundamental reasons for the current difficulty in refueling.