Why birds do not fall while sleeping

This article doesn't even try to address what I feel is the deeper and more interesting question (but probably one that can't be answered): Why is it that horses, cows, giraffes and birds have all had to come up with a purely passive solution of "locking" themselves in place, either via their joints (for the four-legged), or via the tendon mechanism described here for birds?

I.e. why wasn't in simpler in evolutionary terms to come up with some mechanism where 1% of the brain was dedicated to the relatively simple task of "station keeping", while the rest of the brain could benefit from sleep?

Also, why didn't any animal evolve a way to avoid sleep completely?

There's a species of bird (Chinstrap penguin) which kinda does that: it sleeps by intervals of 4 (four) seconds only. Many times through day & night. Can these 4 seconds naps be considered sleep? I don't know, but it goes along your question. Source: https://www.nationalgeographic.fr/animaux/insolite-decouvert...