Specifically wrt to Vancouver, there are some additional things to note.
Canada is cold. Vancouver and Victoria less so. Much empty land is going to be inland and colder.
There is a whole "poverty industry" around the DTES (Downtown Eastside, the place where concentrated homelessness exists) where some providers have a vested in keeping their clients and getting government $. One 20 staff job-help outfit, had, after 2 years and 1.5M$, found 3 permanent jobs for their cares. Another had just pocketed the $ and handed out jobs to their own family and friends.
From the POV of the homeless, it is better to stick in one place that has services and a community of fellows (and illegal substances) rather than to go out somewhere out in the middle of nowhere that doesn't have the resources to cope with them.
Vancouver, outside of the DTES, has a strong sense of NIMBYism. Whenever attempts have been made to relocate people out of the DTES, local neighborhoods have been generally mobilized to keep them out.
The DTES homeless community is challenging in nature. These are not people experiencing temporary homeless conditions. Many have underlying addictions, trauma and mental health issues, along with obvious physical frailty - they couldn't do anything like farm or construction jobs. In earlier times, some might have lived in mental hospitals. Housing them without supervision and support has been problematic in the past. So you'd have to move your health care workers to that "cheap land".
The DTES has also been called one of the largest reserves in Canada. Out of the 7000 or so long term homeless (this is a number about 10 years ago), not sure what the equivalent is now, many are First Nations. That brings its own challenges for the people in question, but also would be a public relations disaster if managed even more harshly.
So to some extent, it makes sense that, in the absence of coercive measures (which I don't think many people would support) the homeless are going to congregate in dense urban areas that already have them, can afford to care for them and are somewhat sympathetic to their plight, at least as a political platform for mayors.
It would also be political suicide for a mayor, or candidate mayor, in many such cities, Vancouver certainly being one of them, to adopt a hardline attitude against homeless people. It is just not what a majority of their constituents want to see done, although that same majority also doesn't necessarily want to spend tons of money "solving" the homeless problem (which might just pull in more from the rest of the country).
A city or country with a more unforgiving attitude towards the homeless might very well have less homeless, but that is a considerable change in worldview to make for many people.
So an uneasy equilibrium persists and you could have seen the same sentiments expressed in many locations 20 or 30 years ago, nothing much has changed. Certainly I recall the "homeless problem" when I lived in NY state and Paris.
Most of this analysis could probably be replicated in such districts like the Tenderloin area in San Francisco.
(Not that I, like many Vancouverites, have not had precisely this idea, but it is unrealistic when closely examined. It's a good talking point, no more. We'd do a lot better working on prevention and avoiding younger people falling into this trap)