Unicode was never designed for ease of use or efficiency of encoding, but for ease of adoption. And that meant that it had to support lossless round trips from

Unicode was never designed for ease of use or efficiency of encoding, but for ease of adoption. And that meant that it had to support lossless round trips from any legacy format to Unicode and back to the legacy format, because otherwise no decision maker would have allowed to start a transition to Unicode for important systems. So now we are saddled with an encoding that has to be bug compatible with any encoding ever designed before.