traditional turnstiles are not always effective, but if you go to cities like Boston, they have electronic gates that are quite high and open only when a validated ticket or pass is scanned. Of course, you still get a few instances where two people manage to slip in on one ticket, but it's absolutely nothing compared to the number of people who ride for free in Vancouver. If TransLink wants to continue with fare inspection as their sole means of ensuring payment, they should ramp up the inspections that take place on buses. That's where people are talking their ways (or sometimes just walking right on without paying) into innumerable free rides.

The cost of the turnstiles will exceed the revenue collected. This would be a revenue deficit result. Besides, people who want to cheat can jump over turnstiles.

I don't think you can ever have 100% fare collection, there will always be some people slipping through the cracks. There has to be an optimal collection rate beyond which the costs of trying to collect from more people outweigh the revenues that could be collected. Besides aren't there worse things you could be subsidizing?

It ticks me off that I pay for transit monthly and I see dozens of people fare evade daily. I love subsidizing other people's ignorance.

You might think so, but experts suggest that turnstiles don't deliver on that promise. For example, see http://stephenrees.wordpress.com/2009/11/23/millions-of-dollars-in-transit-fines-go-unpaid/
Fare inspectors (humans) are a much better way to deal with fare evasion.