The idea isn't that you release less-tested software because you have the canary as a safety net. The idea is that you put in place all of the other practices you would anyway to minimise the likelihood of bugs and mistakes, and then you add a canary rollout as one extra layer of protection to mitigate the damage of anything you missed.

I would look at it as 98% of the users getting an even more reliable experience than they would otherwise (per release; everyone benefits over time), rather than 2% being given a worse experience. The alternative is just that everyone is in the "canary" release and everyone has to immediately use the release you "don't fully trust".