Most commercial installs use mono, only because large installations with lots of speakers use 70 Volt for wiring and power vs 8 ohm. Mono doesn't matter in a mall or other large space.
Residential is different as most everything is 8 ohm and used in a stereo setting. Most rooms will sound great (depending on the speaker/room design).
8 ohm has better bass than 70 volt too, if we are talking the exact same speaker.
Some systems (like VSSL) can set certain zones as mono and can be good for certain room shapes where mono may be better, but these are rare.
Residential is different as most everything is 8 ohm and used in a stereo setting. Most rooms will sound great (depending on the speaker/room design).
8 ohm has better bass than 70 volt too, if we are talking the exact same speaker.
Some systems (like VSSL) can set certain zones as mono and can be good for certain room shapes where mono may be better, but these are rare.