Gotcha, so it's not like the charger "pushes" extra current, but this is only when the load contains sufficient circuitry to prevent overload right? Otherwise why is it a different scenario for applying too much current to an LED? How can an LED be rated for 3V but then when you apply 3V it's too much? I guess I'm thinking of emf as the only variable.
To put it another way, if I'm working on a circuit with 3V, is there a scenario where I can get hurt from 3V? For there to be a high current in such a circuit there would have to be a tiny resistance, which would change the second I touched it (or put myself in series with it).