You mentioned the case of Mexico. I agree that a fair, effective, and fast refugee determination process is much better than a visa requirement imposed on Mexico. I think everyone agrees with that.
That said, though, the mere fact that grant rates for Mexico are somewhere around 15% means that there are quite a few people who are coming here and making unfounded claims, but also that there are still literally hundreds of people in Canada every year who are recognized refugees from Mexico. These often include people making claims based on sexual orientation and people facing gender-based violence. Mexico is not safe for some people.
So then the question is this. Why should the mere fact that there are some unfounded claims coming from one country mean that people who have well-founded claims—sexual orientation and gender-based claims—shouldn't get access to a fair process, with an appeal?