Most likely you are buying from a station that does not have their vapor control vents properly working and the very light combustibles have already evaporated off.
But as you say, believe what you want. I have only worked in refinery design, what would I know?
You can lead a horse to water, but.......
Through an almost devastating experience with pressure build up in a portable, metal gas can, I learned the wisdom of letting the pressure bleed off before use. This was in the ‘60s, long before the ethanol mandate.