All TVs are "HDTVs." That 68% will be near 100% (of TV users) once more TVs die in the next few years.
If I go onto Amazon right now, filter sellers by Amazon.com, sort by low to high, and look at the cheapest two TVs: Samsung UN24H4000 720p: $147.75 and LG 22LB4510 1080p: $159. Both "HD."
So, using HDTVs as a metric of poverty is dumb. They're the only game in town.
Sounds like a nice way to dismiss all Western poverty ever. Have running water and electricity? Clearly not poor...
Just pick anything that 90%+ of the population have: internet, electricity, gas, water, a car, heating, a telephone line, etc and then declare it your "line" for poverty.
I don't think TVs were ever really a luxury in the US, except in contrived Internet arguments about the lifestyles of 10th century kings, where they absolutely always were.
Furthermore, television is a means of mass communication that allows the few media companies to disseminate their own message to a receptive audience. As a cheap source of entertainment, it also occupies and pacifies the public.
If poor people could not afford televisions, they would likely be subsidized. The food stamp program provides the bread, and broadcast television provides the circuses.
How about tracking something that rich folk would be nervous about the poor people owning, like long arms or dissenter-friendly networks? How many poor people own an AR-15 and a software-defined radio?
And the average household size is much smaller than it used to be due to declining birthrates, higher rates of divorce, higher rates of single-parent households, etc.
...also a huge number of people live in low cost of living areas. I have friends and family out in rural areas with perfectly comfortable lifestyles who wish they made 52k a year.
http://www.leichtmanresearch.com/press/030714release.html