I think Debbie raises a very valid point - RoE or Return on Effort. There were certainly issues (non coc related) during the transfer of our house, but the effort that would have been expended to be "right" was just not worth it.

I reckon that in many cases where the owner does become aware of issues with the COC that it is just simpler and less effort to leave it, or resolve it yourself. Less time, less stress, and effectively less money.