This is a bit outdated -- 802.11r fast transitions (FT) allow devices to roam between access points nearly instantly, and 802.11k and v allow access points and

This is a bit outdated -- 802.11r fast transitions (FT) allow devices to roam between access points nearly instantly, and 802.11k and v allow access points and clients to exchange scan results, so that access points can move clients to the most appropriate access point. This does require more than just having multiple access points with the same SSID, and used to be limited to expensive commercial AP brands, but it's quite accessible to consumers these days.