On final approach, GA planes are at idle, and if one is on a mower with mower engine noise, you won't hear the landing aircraft.
But, this airport is not a grass strip, and in-theory, she was not "mowing" the runway (well, some airports with really crappy runways they *do* have to mow the runway). And, if she was crossing it, must of been trained to always and reflexively look for aircraft.
Or, she was talking on her phone
I feel sorry for the pilot, but how could he not see that there was something going on next to the runway? He didn’t see the lawn mower until he was already on the ground? Why not? Nothing looked unusual from the air?
Did he approach from behind her? If so, that was a stupid decision.
I’m sure he feels just awful.