While you're generally right - someone could forego going to school for a few years to save enough that they don't have to go into debt, there are only a few schools where that's a viable option. Yes, theoretically, if someone just took enough time off to work and save, it could be any school. But then the timelines become impractical and you'll probably want to account more and more for the opportunity cost of working a low wage job for an extended period of time. So yes, you're right. But there's no need to be snide about it. And you're just as guilty of gaming the numbers to make your point as jjbean was.
Looking at a couple of rental sites in the Vancouver area, it's tough to find a room for any less than $700 / month. And even there, for a lot of them you're looking at a hefty commute to get to the school. Now that might be a trade off you're willing to make, but more time spent commuting means less time for studying and less time for seeing friends and engaging socially, both of which are healthy, and also go a long way towards exposing you to new opportunities, and helping you find a job.
To be generous, let's say you can find a room close-ish to the university for $700. That ends up being 700 x 12 x 3 = 25k.
You've also forgotten about incidentals and groceries and utilities and everything else. Again, being generous, let's say groceries = $2400 / year, utilities = $450 / year, and maybe you'll give yourself $1000 / year for pleasure, just so you don't become a miserable dick.
That adds another ~$11, 500, bringing the total cost of living somewhat reasonably in Vancouver for the duration of your degree to $36, 500. You could probably do it for less, but I wouldn't be surprised if doing so negatively impacted your performance at school. Unfortunately, doing well at school is a fairly big part of getting a job. Not absolute, of course, but you likely want to set yourself up to approach the job market from the best starting position you can.
And yes, you can work during the summers, but that might involve relocating, or working for a minimum wage, or working for free to gain much needed experience, so you can lop some of that total off, but probably less than you would expect to.
So, for the typical student who wants to do well at a competitive school like UBC, you'll probably want to bank on spending at least $36, 000 on living costs - which, I'll point out, is more than twice the number you're forecasting. That brings your total expenses over $70, 000 - without accounting for trips home at the holidays. Even with the bursary, you're still looking at having to save around $50 000. Again, it's possible, but then you're neglecting to consider the actual cost of spending those years working a lower end job to save money you'd spend anyway. For example, if I worked a $30,000 / year job for three years to save for law school, I could have probably managed to afford the bulk of the expenses I ended up accruing. But it made more financial sense to just finance my education with debt and get my schooling done in three years, rather than the six it would've taken to work and save and then go back to school. The expense of school is a fixed cost over that period anyway. So I had the option of working at 30k / year and then going to school for three years, or going to school for three years, and then working a job that starts around 80,000 and goes up from there. Essentially, over the same six year period, I had the option of making $90k and then spending all my savings (and then some, most likely) on school, or paying for school with debt (the same amount as it would've been in the first scenario), and then making $270k over the next three years.