OK people, thank you all for your sage words of wisdom. I feel suitably schooled. Forgive my ignorance. However, I have a couple points to raise.
First, I didn't realise that there is no absolutely precisely measureable torch output, either between identical examples of the same torch or in any observers/testers ability to measure any torch output that accurately. A reasonable tolerance posited was 10% I think. Well, on a 1000 lumen torch, that's upto 100 lumens either way, which as pointed out will hardly be noticeable. However, on a 100,000 lumen torch, that's up to 10,000 lumens either way. I don't know if that's noticeable by eye but I'd be concerned that my stated 100K lumen torch is actually only delivering 90K worth of lumens. Of course, I'd be smiling more if that same said torch was actually outputting 110K worth of lumens. But this brings me to my second point....
Most of you have asserted that either you or others can and have made relatively accurate torch output measurements, perhaps more accurate than the manufacturers themselves. Well, how do you actually know that to be true? If there is no absolute method of referencing and the testing procedures and testing equipment can vary so much as to substantively affect the results, how do you really know that your own results are that accurate or more accurate than anybody else's results? My point is that without a scientific procedure carried out according to a proven recognised standard, that is repeatable by others and with results obtained being either identical or almost identical between different testers, any claims to having obtained accurate results seems rather erroneous, no matter who the tester was, what they used to test and the method they used to test.
Therefore, it matters little if people claim their testing has produced 'more accurate' results because none of that is verifiable in absolute terms. However, when a manufacturer states their figures which have been obtained under proper lab conditions, assuming they claim the ANSI/..... standard, a casual observer has to believe those figures over those claimed by others who's methods and equipment cannot be verified as meeting or exceeding the conditions stipulated by the international standard. So, why wouldn't the casual observer believe the manufacturer's figures over and above those made and claim by others without knowing whether the recognised standard's conditions had been observed? This assumes that the manufacturer: a) knows what they're doing and b) are truthful about the results they obtained, either of which I'll grant cannot necessarily be taken for granted.