It is an oddity of American health care: Many nursing homes and home care agencies do not provide health insurance to their workers, or they pay wages so low that employees cannot afford the coverage that is offered. The numbers are stark. Among workers who provide hands-on care to nursing home residents, one in four has no health insurance. Among those who provide care to people living at home, one in three is uninsured. The new healthcare law is supposed to fix the problem by guaranteeing access to affordable coverage for all. But many nursing homes and home care agencies, alarmed at the cost of providing health insurance to hundreds of thousands of health care workers, have started a lobbying effort seeking some kind of exemption or special treatment.