Even the best implementations dazzle other drivers.

Auto high beams are only realistic when used where normal high beams are. That is, mostly on single lane roads with no dividers, little to no street lights, where opposing traffic is not appearing often, etc.

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It seems like such a small thing compared to driving a whole car... but this is one of the few vision features that directly affects other drivers on a regular basis.

The comments explain how for example, vehicles with tall ride heights like commercial trucks get dazzled due to their tailights sitting much lower than their mirrors

It's just not realistic to leave your high beams "potentially on at all times" unless you're willing to dazzle other drivers.