NEW YORK (MarketWatch) — Wal-Mart Stores Inc. pushed down prices for some generic prescription drugs to just $4 eight years ago, setting a new industry standard. Now it is trying to do the same for seeing a doctor. On Friday, a Walmart Care Clinic opened in Dalton, Ga., six months after Walmart U.S., the retailer’s WMT, +0.38% biggest unit, entered the business of providing primary health care. It now operates a dozen clinics in rural Texas, South Carolina and Georgia and has increased its target for openings this year to 17. An office visit costs $40, which Walmart U.S. says...