One concept to remember is that the lux at one meter, for the newer, more powerful throwers, can't BE measured AT one meter, as the beam focus has not converged yet. There is a point, some distance from the lens, where the beam has converged, and represents the beam that will be continuing down range to the distant target.
For example, if you shine a triple LED light on a wall, you might see a clover pattern made up of the three LED's and their respective reflectors. If you back up from the wall, the clover disappears, and you see a single, converged, beam.
Its the same for a single LED in a reflector as well, it takes some distance for the light sent from the reflector to form the final beam.
That all means that to get that hallowed lux at one meter value, you must take a measurement far enough away from the lens to have allowed beam convergence. That can be 3 meters, or 8 meters, or even 15 or 20 meters, depending on the light itself.
We then interpolate back to what it WOULD BE at one meter as a mathematical value, rather than as an actual measurement. The reason for that is because listing lux at one meter is useful for predicting the full throw range of the light, and for facilitating convenient comparisons with a standard measurement range....and, the lux at one meter = cd.
So, we measure lux at whatever distance, and then calculate what it would be at one meter, and then publish the lux at one meter/the cd of the light.
A manufacturer can then take the cd, and publish an ANSI throw range based upon it. (No one actually MEASURES the throw at that max range...its always calculated)