AV1 is not about throwing away more data that the human can’t see. It’s about having better tools.

1. the prediction tools of AV1 are better than those of h265. Better angular prediction, better neighboring pixels filtering, an entirely new chroma from luma prediction tool, an intra-block copying tool, more inter prediction tools, non-square coding units.

2. If the prediction is better, the residuals will be smaller.

3. Those residuals are converted to frequency domain with better tools for AV1 as well (more options than just DCT), so that you have a better grouping of coefficients close to the DC component. (Less zeros interleaving non-zero values.)

4. Those coefficients compress better, with a better entropy coding algorithm too.

You can have exactly the same video quality for h265 and AV1 yet still have a lower bitrate for the latter and with no additional decision made to “find out what humans can’t see.” The only place in the process where you decide to throw away stuff that humans can’t see is in the quantization of the frequency transformed residuals (between step 3 and 4) and the denoising before optional film grain synthesis.

To be clear: you can of course only go down or stay equal in quality when you transcode, due to rounding errors, incompatible prediction modes etc. That’s not under discussion. I’m only arguing about the claim that AV1 is better in general because you throw away more data. That’s just not true.