In most industrialized countries there is a discrepancy between the growing daily average prison population and the availability of suitable staff, accommodation and treatment. The consequent overcrowding, and other factors such as out-of-date prison rules, old and unsuitable buildings and lack of suitable work, contribute to the inefficiency of imprisonment.
Prisons are monopoly public services with very low and often negative productivity, and as such are neglected by public authorities. Instead of a correctional system whose productivity would be measured in terms of serving to deter people outside from committing crimes and to stop people inside from doing so again, some prisons create more recidivism than they cure or deter.
Prison conditions vary from country to country. In some countries overcrowding is common and in others isolation is more typical. Some prisons are without adequate heating or air conditioning. Most prisoners have adequate amounts of calories but as a rule the food is monotonous, usually consisting of beans cooked in fatty liquid. Food may be unappetizing and unhygienic and often contaminated with insects or waste products. There may be little meat or roughage. Prisoners may also be plagued by lice, fleas, mosquitoes and other insects. There are frequent cases of illness: hepatitis, salmonella, toxin-induced gastro-intestinal infections, tuberculosis, dysentery and insect-borne infectious illnesses.
In 1973 the Netherlands had 25.4 prisoners per 100,000 population; Belgium had 64.2, France 66, Denmark 71.7, and the UK 72.5. In the UK, with this higher daily average prison population than in other western European countries, guards sometimes had to work as many as 70 hours a week. Between 1951 and 1971, Britain's prison population rose more than 100% and continues to grow, reaching 46,000 in late 1993.