There already are levels of granular control available.
As for increasing the accuracy, that’s a limitation of the source video. A video frame can only cut cleanly along an I frame otherwise it causes tearing of the video. How often I frames are present in the video GOP depends on the video encoding characteristics of the original recording and the format it uses.
Basically if you’re working with MP4 files where you can cut depends on the original video encoding and not the accuracy of custom cuts.