Is there anywhere in the world that has successfully addressed this problem using other methods?

Yes, Not Just Bikes on YouTube has done videos on some. Other mentions are the Autobahn, but that's a special case which is also predicated by the structure of the road system. and Paris has been expanding its efforts to retro fit roads in certain areas into green spaces and pedestrian/cycling infrastructure, which effectively removes speed limits. Not to mention all the eras of industrial society before the personal car became the dominant model of transportation but I get that Pandora's Box has been opened and that evil ain't going back in any time soon but I do fundamentally believe it should be a goal of getting back to.

I'm not saying speed limits are completely useless but you have to first take in the material conditions of the road and understand people are going to drive at the speed that is most comfortable to them. That's just how humans generally are. That's why I mentioned that most speeding is simply an absent minded mistake. Paying strict attention to the speedometer slipped their attention among the many other things you need to keep observant of while driving or just simply were pulled into complacency by a boring, routine drive

It just isn't an effective method of trying to force people to drive at an arbitrarily predetermined speed even if the road conditions are safe to do so. Also, due to the systemic structures which dictate the overarching experience that I personally find unjust, I fundamentally oppose a political entity having the hierarchical authority to take away someone's means of being able to travel or imposing financial penalties but that's getting into much deeper politics than I care to get engaged with. I'm too tired for that right now