Oil consumption; why some, not others?

At least one study found a major cause of oil consumption to be reverse blow-by. The oil gets sucked and flung into the combustion chambers.

High fuel dilution makes the oil more easily combustible so that will increase consumption as well.

Low tension rings increases it.

Piston and piston ring deposits decreases ring seal and ability of the rings to scrape oil from the cylinder walls. That increases oil consumption.

Some oil enters the CC past the valves when their is a partial vacuum in the CC.

Some oil is sucked through the PCV system and burned in the CC.

If by consume I think you mean burn essentially. Only really 2 place for oil to get into cylinder where then burned up; first along valve guide, down stem, around valve head, and then into combustion chamber. The amount thru this route is very small unless very worn out guides. That leaves the second route: around the ring pack. This is the big variable and will allow a lot more oil into cylinder. Some manufactures use low tension rings for either hp or mileage benefit. The looser rings have less friction, and seal up less well, and scrape off less excessive oil film on cyclinder walls. I think this why some use oil and some don't in a otherwise mechanically sound engine.