So, therefore, people are losing money, quality, and product. Another reason taxes aren't fair is authorities require the buyer or seller to be LEGALLY responsible for payment of tax, which if supply is in elastic for produces, will increase the burden on producers and the buyer / seller.
A subsidy shifts either the demand or supply curve to the right. For example if the supply shifts right, product demanded will increase, while the equilibrium price decreases.
A quota limits the amount of good that can be produced. For example if quota is greater, nothing would happen, but if quota is lower, equilibrium would be at a higher price.
Deadweight loss is the inefficiency caused by tax or monopoly pricing. By causing difference between pre and after tax, the government secures their share from the consumers.