I think your question gets at the salient point: I often think of the concept of "ownership" as black and white, I either own something or I don't. But in practice it's a gradient.

At one end of the spectrum, I pretty much own the clothes on my back and the items in my pockets. Sure, they're stolen occasionally in muggings (hasn't happened personally, knock on wood), but on the whole I spend no time in court or with police arguing over an ownership dispute about my underwear.

Any why is that? After all, my clothing is relatively nice and well looked-after, and the items in my pockets and on my person, including smartphone, wallet/cash, and watch are worth north of $1,000. If I were to leave the clothes and items in a bag on the sidewalk with nobody to look after them, the likelihood of their theft within the hour would skyrocket. So why am I not mugged every hour? Well, I think it boils down to the fact that I'm physically "there" wherever I go. Mugging me requires a certain level of brute force to make sure I don't fight back. Which is, relatively speaking, harder to come by than the effort required to pick up a bag of items when nobody is looking.

At the other end of the spectrum, let's say I own multiple properties in multiple locations. These real estate holdings can't be "stolen" in the traditional sense, but they can be occupied and used by people against my wishes. So how do I stop that? After all, I can only be physically present at any one property at a time. And even then, if it's a big property, I can only "guard" a portion of it. So how is it that I'm able to own all of these properties? It's the system of police and courts that makes this possible, and consequently I do spend a lot of time in court or with police arguing over contracts, tenant disputes, etc.

This "ownership" is only possible because of the system of laws and courts and police, paid for by the taxes of everyone. And so the voters that pay the taxes that allow these systems to work are naturally going to want a say in the matter. If I own a piece of land downtown, adjacent to a school and houses and office buildings, and decide to start pouring toxic waste onto it, the police and courts will not come to protect me while I'm doing so. They'll come to stop me. Even though I "own" the property.

And that's what's happening in Vancouver. These absentee property owners are not suddenly being deprived of their ownership. The change is actually happening right at the margin: the voters have decided they'd like to tweak the laws a bit so that the police and court resources they support aren't being spent to protect empty properties.

Now, is it right? Certainly I can see why the property owners are mad. They bought in expecting a certain set of laws to be enforced, and instead a new set is imposed. Which can also impact overall business and regulatory confidence. Delaware's popularity for incorporation is built upon its long history of changing its regulatory environment as little as possible, and trying to be as predictable as possible. But the situation in Vancouver is showing that there may be more latent unpredictability in regulatory and legal systems than is commonly thought.