It is so expensive because the course is required to be a minimum 120 something hours long.
It surely does put people off without a doubt although many Canadian citizens can get government loans or grants to help with funding to one extent or another depending on individual circumstances. This is not available to people from outside of Canada of course.
To understand why any of this legislation has been created look up the Humboldt, SK tragedy on the internet.
The only good part of all this is that a CDL driving license, by virtue of being harded to obtain, also becomes more valuable although that is small consolation to the person who is yet to obtain it.