I don't think (most) benefits are withheld in canada (or in europe). The point of probation there is to provide an initially relaxed (labor protections wise) 3~6 months "at will" to check for actual suitability since you don't really know whether things work out until work's actually been done. Breaking the relationship later is a more involved and expensive process and the thinking is that within the early 3~6 months the employee would know whether they want to stay, and the company whether they want to keep.