Snip... ...A
couple of years ago, the frequency was also allocated here in Arizona to a
local commercial operator for ground to air operations.

For the record...and making no claim to be an FAR/CFR anal wizard, my
understanding (from my instructor and eventually from reading material over
the years) has always been 123.3 has NEVER been "a glider only" frequency in
the U.S. I *think* 123.5 similarly was allocated for multiple - if specific -
users. Feel free to look it up.

In any event, flight school use has been a written-into part of 123.3
allocation since at least 1972, I believe.

Mostly, it's been ignorant glider pilots who (mistakenly) have thought of
those two U.S. frequencies as "exclusively for glider pilots". I'll wager a
good beer the Arizona commercial operator somehow or other selectively
read/heard what he wanted to regarding others' legal right to be on 123.3! Why
should glider nuts be the only misguided souls on the planet?

Bob - yeah it's still winter in the northern hemisphere - W.