The ASBC (and I believe EBC) tables are for density measured in air at 20 °C relative to the density of water, in air, measured at 20 °C.
I'm wondering if breweries adhere to the ASBC's standard when taking their own measurements. I would assume there has to be some standard amongst brewers, especially in the commercial world. Maybe my best bet is to call a few breweries and ask.
Certainly any brewery of any size will use the ASBC protocols and many craft brewers will too. The question was is there an industry standard. In the USA the ASBC represents the industry. Whether a particular brewery adheres to the standard or not is another matter.
The temperatures can make an appreciable difference. A wort of 1.04000 true @ 20/20 °C would measure 1.04184 @ 20/4. The difference between true and apparent is less dramatic.