Efficiency and standards

Capacity and cost are both considerations when purchasing a washing machine. All else being equal, a machine of higher capacity will cost more to buy, but will be more convenient if large amounts of laundry must be cleaned. Fewer runs of a machine of larger capacity may have lower running costs and better energy and water efficiency than frequent use of a smaller machine, particularly for large families. Running a large machine with small loads is wasteful.
For many years energy and water efficiency were not regulated, and little attention was paid to them. From the last part of the twentieth century increasing attention was paid to efficiency, with regulations enforcing some standards, and efficiency being a selling point, both to save on running costs and to reduce carbon dioxide emissions associated with energy generation, and waste of water.
As energy and water efficiency were regulated, and a selling point, but effectiveness of rinsing was not, manufacturers tended to reduce the degree of rinsing after washing, saving water and motor energy. This had the side-effect of leaving more detergent residue in clothes. Insufficient rinsing can leave enough detergent in clothes to affect people with allergies or sensitivity.