Wifi uplink air interface
Wifi is fully symmetrical meaning up- and downlink signals are identical. Both are OFDM modulated and on a fixed channel.

In Wifi the allowed transmitter power level is much smaller (a factor 10 or so) so efficiency of the PA (Power Amplfier) is less of an issue.

Note that SC-FDMA still uses OFDM but for a single channel only !
I guess that this is done so that the bandwith of the PA in the handset can be less, making it more efficient.