Taxing sales and services (as opposed to taxing income) is seen as a simpler way of collecting tax at the point of sale. People can avoid paying income tax by not declaring cash income or using unfair loopholes, but as long as the seller/service provider is not running a cash business off the books, the purchaser cannot easily avoid paying sales tax.
Sales tax is a flat tax, not a progressive tax, so it is more burdensome to poor and middle income individuals than to wealthier individuals. In most states sales tax is not charged for many essential items such as food and medical services. In the U.S. three states have no state sales tax, Montana, New Hampshire and Oregon. Local taxes of 2-4% are often applied in addition to state taxes.
Some argue that only items/services contribute to the burden that states must manage should be taxed, for example, junk foods that contribute to the public health problem, alcohol and recreational drugs, gambling, tobacco, and plastics. These are called consumption taxes.