You’re comparing an OS with a specific device. In the union case (Asahi Linux on MacBook), the battery life is much higher than 3h. Not yet 13, but soon should be close.
Let's hope it will be close. MacBook has twice the battery capacity as a run of the mill thinkpad. So 6h of battery would be the default I expect. More than that, and I will be impressed.
Note that I have been using Linux for 20y. And I fully accept the short battery life in exchange of the tooling and freedom I get with Linux.
