I have no issue with lossy compression; but things like 4:2:0 aren't really typical lossy compression. It's like calling resizing an image to half its resolution "compression".
Also lossless compression can reduce plenty of "wasted" bits already (see: png vs bmp).
But they are ! Like other lossy forms of compression, chroma subsampling takes advantage of the human visual system's lower acuity for color differences than for luminance.
Also lossless compression can reduce plenty of "wasted" bits already (see: png vs bmp).