There are many wifi mesh protocols, most are proprietary that will NOT communicate with other wifi equipment brands (e.g. Apple, Google, TP-Link etc.) locking customers in.
Some wifi equipment do include standards based wifi mesh protocols (e.g. WDS, 802.11s etc.) they are generally limited in features and do not perform as well as proprietary meshes technologies included in those equipment.
To overcome the above limitations the community based batman-adv wifi mesh protocol is used.