I have understood that the oil consumption between cars varies a lot, more than an order of magnitude. And by this I don't mean that a specific model of car consumes more oil than another model of car, but that two identical cars with identical engines and identical miles on the odometer can have different oil consumption, with one consuming 10x as much as the other.
My own personal experience is that I have had three cars long enough to say something about oil consumption: a 1989 Opel Vectra which didn't burn oil but suffered from oil leaks late in its life, a 2011 Toyota Yaris that burned oil but only so little that you didn't have to add oil between oil changes, and a 2016 Toyota RAV4 hybrid with only 3000 km on the odometer for which it is early to say a definite answer about oil consumption but it doesn't appear to be burning it a lot.
Why do some cars consume oil by burning it, even during early parts of their life? Can't the manufacturers consistently build good engines for which the oil consumption is minimal? The acceptable oil consumption specified in the manual, which is usually something like 1L / 1000 km is absurd, meaning you need to add oil over 10 times during a 15 000 km oil change interval.
Of course, a genuinely worn-out engine can easily consume lots of oil, and of course all engines consume some amount of oil. Let's limit the answers to why some relatively new engines consume so much oil that you need to add more oil.