My issue with the strict enforcement of speed limits is that safe speed for a given stretch of road varies drastically based on conditions. These would include weather, light level, traffic density, vehicle capabilities and condition, and driver experience and aptitude.
It's not possible to set an optimal speed limit for all these conditions, so normally speed limits are set quite conservatively. Of course it is theoretically a limit, not a target, so you could instead set it closer to the target speed for ideal conditions and expect people to slow in other conditions. That is done in some parts of the world, but not most. And so in somewhat of a causal loop, many drivers therefore consider the speed limit to be a target rather than a maximum, and don't apply a lot of judgement in determining safe speed.
My belief is that (with sufficient time and training to reach a status quo) a system with less strict or no speed limits, and instead a focus on safe driving, would encourage drivers to be more thoughtful and attentive, and result in fewer accidents and possibly even fewer injuries and fatalities. This could include design elements such as traffic calming where appropriate to encourage an appropriate speed without using conservative speed limits. Perhaps an increase in consequences for at-fault collisions would make sense in conjunction as well.
I do recall seeing some evidence that increasing or removing speed limits can reduce collisions, although perhaps not fatal ones. On the other hand, I can certainly understand if one did believe that lower speed limits save lives, one could argue it's better to over-enforce the limits and risk wasting people's time than under-enforce them and risk wasting lives. Also any increase in legal subjectivity increases the risk of unfair enforcement. So I don't think there's necessarily an obvious best approach.