Reverse lockout linkage makes sense....didn't know there was such a thing. I learned something new today. I don't believe that there is a finger switch at the key.
There is, it's a little 'shelf' built into the portion of the column that would be where the shift lever mounts and pivots when shifting gears on an automatic or column shift car. It has a little decal with an arrow that says 'reverse' on it.
You can kind of see it here
And I think that's why they give you the reverse light, right? So you know that you're now able to shut off the engine, turn the key and lock the column.