No data, but I am aware of this: aircraft buckles are different to car buckles. On the face of it, that seems crazy to me. The aircraft ones open by being pulled or lifted, where car buckles need to be pushed. People have died in 'plane crashes because in a crisis they reverted to the car system they were familiar with, and it doesn't work on 'planes. The aeroplane safety lecture explains how to unfasten their belts in an attempt to over-come that.

So, given the apparent life-saving advantages of changing aeroplane buckles to work the same as car buckles, I assume there is some major overriding benefit to keeping them as they are. I'd guess they were more reliable and less likely to jam.

(PS I too thought the original post's mention of air travel meant this was more about aeroplanes than cars.)