I hope we all agree the problem doesn't go away because you don't see itI haven't seen this problem.
If you don't believe this is how they work, here are some references: http://www.extremetech.com/article2/0,2845,1734387,00.asp
"As the APL [Average Picture Level] increases, power and heat dissipation restrictions reduce the maximum brightness that can be safely produced, so the display automatically reduces the peak brightness. When 100% of the pixels are at peak white, the brightness is only 53 cd/m2, which requires subdued ambient lighting for good viewing. "
http://www.practical-home-theater-guide.com/lg-plasma-tv-2010-2.html
"One review site noted that these LG plasma TVs suffer from a similar problem encountered on Panasonic G20/25 and S2 series plasma TVs, namely that of fluctuating black levels with different average level picture content, though the Panasonic picture is a bit more stable.
Unlike LCDs, all plasma TVs do this to some degree and happens as plasma display technology tends to adjust the overall brightness depending on the average brightness of the picture - also referred to as average picture level (APL) - to prevent panel overheating and excessive stress, and to extend the panel's life."
http://www.hdtvtest.co.uk/news/panasonic-tx-p42c3b-tx-p42c3-201103211056.htm
"we did see luminance levels (and Greyscale tracking) shifting around during the Average Picture Level pattern from the AVSHD test disc. This is very common for Plasma displays, and is a reminder that, although we didn’t see anything during viewing, some sort of low-level luminance fluctuation is possible."
You can read about ABL or Average Brightness Level circuit in Plasma here: http://www.energystar.gov/ia/partne...sions/downloads/tv_vcr/Weber_Presentation.pdf
http://www.hdtvtest.co.uk/news/panasonic-tx-p42vt20b-tx-p42vt20-20101110913.htm
"We’re used to seeing some brightness fluctuation from most Plasma TVs and often observe the same effect when we display a 100% windowed test pattern during Greyscale calibration, so we’re not surprised that slight inconsistencies can pop up in real world content."
I will stop here....