Well... yes, you're right. But usually, when you make a mistake, you say so. You don't pretend nothing's happened and moved on to doing something completely different without any explanation, do you? Well, unless you are a politician, of course, they do that all the time. Hence why population here mistrusts them. Because they are liars.
See, honest people would stand up and say "Ok guys, we're sorry... we failed. We intended to do X, but we failed and now we have to do Y, we're really sorry about that."
Not "Lulz, we said X but you know, Y is cool, too and we planned this the whole time so you don't need to worry about it!"