I have no idea if Tariffs will stop anything but what I do know is tariffs will get the offending countries attention as they already have with the mere mention.
How do tariffs stop illegals sending money home? It doesn't, what it does is encourages these countries to work with the US to stop illegal immigration and accept their criminal element back when deported. This will in turn reduce the problem and keep it from getting worse.
Donald Trump hasn't told me anything, it's simple common sense, something you obviously have disregarded on this issue as it defeats your position.
Bottom line, like I have tried to explain to you before, tariffs are a economic tool to encourage countries to do the right thing. Sometimes the mere threat of implementation is enough, sometimes it takes the countries feeling the pain of the tariffs and sometimes they do not work which require further action. When diplomacy is not enough, as they obviously haven't been, tariffs are the next step to encourage cooperation. Again all common sense.
From what Ii can tell your position is to ignore all the problems, do nothing and just accept them. I don't ignore problems, I look for solutions.