Duhhhhhhhhhhhhhhhhh, you don't really think advertisers would lie about their products do you? And Lumens are so subject to companies lying it's insane; it's the same extent of lying that goes on when you buy a stereo at Walmart or Best Buy (or the like) and they claim a 580 total rms watts when in reality it's closer to 75!! It's the same with politicians too!!!!

Consumer protection laws? Those laws and law makers and agencies are a joke; there is so much false ads on TV and radio it makes my head spin, yet consumer protection law makers know these ads are out there and still don't do anything about them. So good luck in getting any help through any consumer protection agency.

As far as light output goes your best protection is just to read reviews on various lights, view images of them as the one site you posted, and try to find some on display at an LBS and try them in the store. The best way is to actually try the light on rides IF the LBS will allow you to return if your not satisfied with the output or pattern.

In my opinion though, most of todays higher output lights put out more light then necessary for road use. You don't need 900 lumens traveling at 25mph, in fact you don't need more then 300, but then again I don't suffer from night blindness and I find that I have plenty of light with just a 13 watt halogen traveling at 25mph. That doesn't mean though that when my light dies that I won't get a brighter one, but would probably get either a 16 to 20 watt halogen or a 200 to 250 lumen led. (EDIT) I do run a helmet light, but it's about 100 lumens in a semi flood pattern, and I run a flasher but only to attract attention, it obviously does not light up the road.

Do you realize that you can get a light so bright, such as those 700 to 900 and more lums lights, that your eyes pupils are smaller to let in less light due to the brightness of the light reflecting off the pavement back into your eyes that the surrounding areas outside of the light pattern are virtually blacked out thus you can see very little detail going on in the unlighted or dimly unlighted areas? Just a thought.