Separate discussion. I was responding to the "they can't prove it" argument.
Haven't proved anything... you say probability, which is not certainty. Unless there is a physical corner, with a documented survey on how that corner is set, the basis of which it's set, everyone is just assuming its where it is and guessing whether I actually stepped on private or not. Short of the landowner standing next to me with a surveyor, or physically proving EXACTLY where I was standing and then having it legally surveyed, Pretty good odds that is a reasonable doubt.
But really, if you don't have the balls to step over the corner, you might as well just stay on the other side..

Growing up in a Surveyor's household, I was slipping through sliver's of public land 20 years before OnX was even a thing, and now I've got zero problem crossing a corner in the states of 10th circuit until ruled otherwise. On a sidenote, I've seen plenty of survey markers set by PLS's that were completely off too...
A bunch of the section corners in the West are piles of stones, or marked flagstone, some buried. Also many of the survey grids are based off different meridians, and there are even adjustments to sections made due to surveying errors made over a century ago. There are always boundary discrepancies. You could have 5 different surveyor's legally set your property corners and some might be a little different than the others, the margin of error less on smaller parcel's of land. Many of the early surveys were measured with rods and links, steel chains, then laser distance meter's and now GPS. Also survey instruments now have a tighter tolerance on angles. The earlier tools being much less accurate... Clear as MUD right?