[pmjordan]

For what it's worth, crows in Central Europe have been doing this for decades. They (carrion crows) used to do it outside my childhood home in Austria ~25 years ago. (Very light traffic, so no traffic lights; they just put some nuts in place when they heard a car coming.) They would generally first attempt to crack the nuts simply by dropping them onto the road from a height. I guess they left the ones that didn't crack on impact at terminal velocity for the cars to deal with.

There may well have been multiple independent discoveries, and passing the skill on between individuals and generations has probably made it near-ubiquitous now.