Hold on people, its not like that at all.
Though there are scammers out there that you should watch out for (some prominent USA led branded names for example, and/or China) the rated power vs actual power draw is a common practice in the LED world. They are not being dishonest at all in most cases. LEDs are manufactured to be under run so as to maximize life expectancy. 1W vs 2W vs 3W, lens angle, power supply, cooling/temp, even quality of local electricity may factor in and give different readings. Most companies will give you both, rated and actual power draw. If not, ask. (for instance: in the link you posted, in the bottom graph, you can see 50 x 3w but average rating is 100w)
What they do is give the idea of how many led chips. Remember most can be easily upgraded. So 50 led x 3W = 150w to work with. Bridgelux, Cree and Epistar are all differently spec'ed, and many combine different brand LEDs for optimum power and light spectrum. Usually, 2W and 3w are actually 1.5 - 2.5w. Some even as much as 50% less. This is not bad, its actually better.
Some companies even rate based on actual power draw, but even that is dependent on temperature, cooling, humidity etc etc... You have to keep a keen eye.
What you should do is calculate how much actual power draw you need for your area. There is no consensus, impossible right now, way too many variables, but what I am seeing is that 90% say that "it replaces a 600w HID !!" - it depends a bit. Too many brands and ratings. One man's 500w can draw 250 with very very high PAR (photosynthetic active radiation) penetration, while another 500w can draw 380w but with a very low PAR. Or the exact opposite. In this regard, traditional lamps are more reliable to "calculate" how much you need.
Personally, I just got 2x Blackstar 3w Bridgelux / Epistar 240w with IR and UV. Total of 480, total actual draw of around 300-360w I expect (haven't arrived yet lol). I hope this substitutes my 600w HPS handsomely, with better light spectrum as an added bonus. I spent a total of 320€ with shipping from China to my door. If not enough, 3 of these (720w) will certainly outperform a 2500 dollar/€ "super good branded" 900w LED that is overpriced.
(with a grain of salt of course, I hope you get the idea).