Yeah I was thinking a lot about that yesterday.
My theory is that modern training supported by AI and computer analytics have helped kickers become more consistent in their technique. Sort of like how golfers similarly work their swing, it seems kicking can be honed in that same way with modern training and technology. Plus I think kickers are much more athletic than they used to be - all the players are.
Also I wonder if full-time long snappers, holders, and dedicated regular practice time might help with the repetition that helps produce consistent accuracy. Not sure how much that has changed.
But it certainly suggests that something about the modern, active kicker yields more consistent, accurate kicking than it used to. I'd like to see the make percentages for FGs from 50+ and 40+ compared by decade. That would be interesting - based on what we're seeing, I imagine that the numbers have improved if, say, you compared 2010s to 1990s.