Returning for a moment to the 19th century tow hook designs that are on most tugs.

Why does the pilot need to pull the release if the glider kites? Why is the release for a deadly tow position not fully automatic? Is a simple purely mechanical, totally foolproof and 100% automatic release not possible?

As the guy in the glider, I would be fine with a 100% automatic release. If I kite, release me immediately.