High intensity rear led lights

In my opinion,,,
all LEDs dazzle, there is no requirement for them to be focused/directed, apart from oem headlights.
Tail lights should be of the specified brightness to save confusion from brake lights.
Fog lights should only be used when the visibility is 100m or less and rear fog lights should be switched off again as the weather improves or another vehicle is behind you

All of which is true, but these are of the "speciifed brightness", that's the point of carefully reading the Vehicle lighting regs and noting the age cut offs for the various requirments.

That’s OK then.

Does it mention how bright they actually have to be to wake someone up.

Or indeed become visible through several cars when lighting a fag.