I think LEDs put out more light than most people would imagine. The trick is to use a simple footcandle meter instead of a fancy light meter. I remembered I had a Rapitest multi testing meter for gardens, which has a light meter as one of the things.
Here's an Amazon page for just the light meter by itself.
Full sun is 10,000 fc. According to the meter, one of my little clone veging chambers with a 5w LED bulb puts out 5000 fc at plant top height, about 8000 right at the diffuser. To convert fc to lux you pretty much just multiply by 10, so that would be 50,000 lux in that 5w chamber. That's pretty high. The bulb is only rated as 450 lm. How do you suppose a 450 lm LED cranks out 50,000 lux?
The chamber is about 1 sq ft area, about 1/10th of a sq m, all mylared inside, it's 5000 fc anywhere in that area.
Here's where I got the thing about lux being 10x fc. The big flowering chambers are 8000 fc at plant height, with the combination of HPS and LEDs. With the bottom lights I use, it's actually no less than 5000 fc anywhere in there above pot height.
So what do you make of this? Unlikely the light meter could be off by that much. Granted it's cheap but still, somebody would have noticed by now and complained to the company.