Compared to ZigBee or wireless M-Bus wireless LAN is some kind of classic communication technology; developed in the 90s. WLAN / wireless LAN is the RF technology - the protocol - WiFi is a consortium consisting of many and big companies, called the "WiFi-Alliance". This alliance offers fee-based testing and certification of WLAN devices.
The biggest advantage of WLAN is probably the ultra-wide spread or usage; each smartphone has RF modules inside, which can operate in different modes - station / end-node as well as hotspot / access point. Both in private and commercial / professional environment in most cases an existing infrastructure can be used; therefore a separate gateway is not needed..
The crux of WiFi is the complexity of the stack, leading to a higher energy consumption of the controller. Other RF network protocols like e.g. ZigBee are developed right onto the main requirement of ultra-low power and long battery endurance - from specification up to implementation. Therefore, transmitting reliable sensor data - battery powered and for several years - is probably a subject to other, newer wireless sensor technologies.
are just in development / test process. Unpacked or brought to factory default, the devices behave like an access point. With a smartphone or any other WLAN device the network can get joined. The device can now get configured properly via a web broser: