Full midday sunlight is about 100,000 lux. Recommended illumination levels for office buildings are 300-500 lux. Domestic rooms will often be lit at less than 100 lux.
My workbench is illuminated to 10,000 lux, which compares to common daylight conditions. Just lighting that small area requires 120 watts of high-efficiency LEDs. Lighting the whole room to that level would require nearly two kilowatts of LEDs. Most "super strong indoor lighting" is in fact very dim compared to sunlight. We don't realise it, because our visual system is incredibly adaptable to changing illumination conditions.
I feel like it's not directly comparable because light gets reflected around indoors. I imagine having full sunlight indoors would turn everything white.
Illuminance (lux) is a measure of the amount of light falling on a surface, not the amount of light being emitted. Any reflected light will count towards the measured illuminance.
Sunlight is just incredibly bright. There's a reason why film crews often need to use huge metal halide lamps powered by a generator truck - it takes an immense amount of power to compete with daylight.
You can just use a light meter to measure directly.
Normal indoor lighting is a few hundred lux and with the right setup, I was able to increase it to 1000 lux at where my head is generally physically located.
My workbench is illuminated to 10,000 lux, which compares to common daylight conditions. Just lighting that small area requires 120 watts of high-efficiency LEDs. Lighting the whole room to that level would require nearly two kilowatts of LEDs. Most "super strong indoor lighting" is in fact very dim compared to sunlight. We don't realise it, because our visual system is incredibly adaptable to changing illumination conditions.