Frequency response + or - 1 dB ??

I appreciate the comments explaining why the posters feel flat frequency response is not important.  I’m not arguing. 
I’m asking why speakers generally aren’t able to be manufactured with level frequency response. Still hoping for some information. 

FWIW  Revel Salon specify +/- 1/2 dB from about 29 to 18,000. They are also the longest lasting reference level speaker that has remained unchanged. I find that interesting when most manufacturers seem to make changes simply to make a change. I think the Salon’s uniquely sculpted face also leaves little room for improvement in dispersion.  Also interesting as only B&W seem to also have a significant design to eliminate dispersion 

Ptss, you can make speakers pretty close to flat when tested in an anechoic chamber. There will be some unit to unit variation. The problem is that once you put them in a real room their response curve changes. The Japanese tried to design loudspeakers this way and they were awful. It is impossible for a speaker manufacturer to predict let alone compensate for the acoustic environment their speakers will be placed in. If you want to be assured of flat frequency response get headphones.

How do they, the various speaker manufacturers, measure frequency response? Do they use the same anechoic chamber? Their own anechoic chamber? Is there a standard for anechoic chambers? Or some other kind of specially constructed room? One wonders if they construct a room that produces a flat frequency response for a particular speaker, if you see what I mean.

Why is it hard to get flat frequency response, on axis, in an anechoic chamber? What is it about the drivers that needs “technical” improvement? We’ve put men on the moon, extreme precision required; what’s the big deal with loudspeakers. With the amounts charged for the “spensive” models — I expect better; more accuracy.