When I fill up my almost-empty car (20 year old, diesel engine), if I pump 50€ worth of gas, the needle goes up to 55 or 60%, tops. But to get a full tank, I only need to pump another 15€.
Why is it so non-linear? Is it just old and out of whack? Is there a design choice in there? What am I not getting?
As others have said it’s surprisingly difficult to measure volume of level in gas tanks for a lot of reasons. So no it’s (usually) not a design choice, worse in some, better in others.
My first car had no gauge at all and you had to estimate by distance. Wasn’t much of an issue either.