You can manufacture Wireless Ethernet hardware. E.g. 802.11b, and sell to every one.
But you want to go fancy.
So you pay to the WIFI organization. They Test your hardware and certify that it complies with the 802.11b standard.
You can then proudly put the WIFI sticker on your product's box.
Link:
What is WiFi?
Most of the Entry Level Wireless manufactures do not bother to go through this certification (It cost money, and it delays the product availability.).
At the moment it seems that this symbol is not of a significant value at the Entry level market.
However it is a
Very Important to use WIFI hardware in case of businesses and organizations that invest a lot of money in Wireless Network, and have large Networks and Multi Sites..
As Long as they use WIFI hardware (even from MultiBrand) the systems will be compatible and will work similarly.
:sun: