Re: Er....
I don't know why a USB 2 charging port is 1.8A and a USB 3 charging port is 1.5A, but I'm guessing it's because I've misread/missunderstood something.
Because USB Charging over the traditional cable was always limited by the spec to 1.5A. It's just that many devices push the envelope towards 2A. Type-C cables BTW are allowed to go up to 3A by spec.