Besides being illegal, they're also expensive:
According to a 2011 report from the Government Accountability Office, Medicare makes an estimated $48 billion in “improper payments” each year, an estimate that’s almost certainly lower than the actual amount since it doesn’t include bad payments within the prescription drug program.
Fred E. Dweck was a surgeon and director of a healthcare business in Miami who swindled Medicare out of $24 million. How the fraud worked:
Dweck’s gimmick, like the payment system he was manipulating, was simple: He gave the go-ahead to official orders for prescription drugs, staff-assisted insulin injections, in-home visits by nurses, and an assortment of other treatments for an estimated 1,279 different patients, none of whom actually needed treatment. With the help of five nurses who faked bundles of official patient records and payment forms, Dweck raked in cash on the taxpayer tab.
The Dish 