I think the marketing of prop 13 was old people getting kicked out of their houses.

But I think the majority of the tax avoidance goes to not-old-people, like immortal corporations that can own the land forever.

EDIT: random link - it seems like residential owners don't benefit anywhere NEAR as much as commercial, rental and industrial entitites.

https://youngamericans.berkeley.edu/wp-content/uploads/2023/...

The linked study in OP shows that the single biggest beneficiary of Prop 13 on a category basis was vacant land.