They're mostly undocumented migrants, they're migrants who shouldn't be in these countries and that makes these people vulnerable.
As you said, it's a context where human rights can easily be trampled on, such as the right to security of the person, the right to work and the right to education. Children don't go to school in transit countries, for example.
This is a situation that requires a hemisphere-wide response. We need to work together to find a solution, because this is happening in our backyard. Canada is doing very little to try and solve this problem.