Why do pirates prefer hevc over AV1? I assume they don’t care about intellectual property so I assume it comes down to technical quality of the algorithms? Maybe they have moved to av1 and I just don’t know it. Either way the quality of the piracy scene has always seemed vastly better than legitimate channels, up until Netflix.
And since web streams are in h.264 and h.265, that's what the torrents are in too. It's not about preference, it's about the source.
(And the web streams are in h.264 and h.265 because that's what people have the most hardware decoders for, which preserves CPU usage and battery life.)