RYR forgot to get landing clearance
I was an ATCO for over 30 years & witnessed several aircraft (from well known airlines) land without receiving a clearance. On every occasion it was not a big deal. There was no other a/c on the runway (or cleared onto the runway - & I kept a good look out for any incursions). I just let the lander continue to touchdown without making a fuss.
In these circumstances I did not feel the need to admonish the pilot, simply to remind him of the need to receive a clearance before landing (once he had landed). I think safety was served just as well by this procedure rather than going into print on the occurrence.
Perhaps, by doing this, the pilot was embarrassed sufficiently to make sure that he never did it again !