The Myrtle Beach area is not a compact city. It is a strip of beach towns stretching from Pawleys Island and Murrells Inlet in the south, through Surfside Beach, Garden City and Socastee, up past North Myrtle Beach to Little River and the North Carolina line. Inland, Conway and Carolina Forest keep adding subdivisions. Someone typing a query in Garden City sees a different map result than someone doing the same search near Barefoot Landing, and Google treats those as separate local markets.
Visitors search from somewhere else
A family in Ohio or Pennsylvania picking a condo, a tee time or a seafood buffet is searching from home, weeks before arrival. They use destination words like "North Myrtle Beach oceanfront" or "Murrells Inlet marshwalk dinner", and they compare listings on travel sites before they ever reach your site. Ranking for them is about topical pages and trust, not proximity.
Residents search from right down the road
Retirees who moved to the coast, young families in new builds along the bypass and workers who stay year round search with near me intent. For a plumber in Socastee or a pediatric practice in Conway, the local pack and the Google Business Profile carry most of the weight, and reviews from nearby customers decide who gets the call.