Slacks implies pants of certain materials which are not part of a suit (jeans are not slacks, and you would not refer to the pair of trousers that came with a suit as slacks.) It is also more common to use slacks to refer to pants worn by women, while men would wear trousers.
Health care safety net providers are those that have a legal mandate or mission to offer medical care to all patients, regardless of their ability to pay, and have a substantial number of patients who are uninsured or on Medicaid.
The purpose of uninsured motorist coverage is to pay for your medical bills and property damage expenses in the event the at-fault party in your car accident case does not carry any automobile liability insurance. In a situation like that, you may choose to sue the at-fault driver.