davedek... You sound mightily amazed, which suggests you are not a controller! We could fill plenty of books with stories of PPLs getting lost and causing major problems. I was on watch when a Flying Instructor decided to show his pupil Windsor Castle one sunny Sunday morning - the carnage which ensued was amazing. I don't know if he was prosecuted but the punishments are (or were) pretty mundane. If someone who can afford to fly gets a couple of hundred £ fine it's probably small change.
ATC can track wildies (as we call them) but only for so far. If the aircraft is low it will soon go out of cover. Of course, if it has a transponder switched on that can help.
The excuses are brilliant: "I was flying xxx VOR but they seem to have changed its frequency so I was 20 degrees right of track".... "I was following a main road but my map must have been out of date".... "The plane had just been serviced and they couldn't have re-set the gyro correctly". The guy flying from Denham to Elstree, who ended up 3 miles east of White Waltham heading southwest was the best: "I must have misread my compass". And a CL-44 (yes!) went straight through the London Zone once at low-level. He'd taken off from one of the airfields north of Heathrow heading for Lasham and the controller at his departure airfield said something like "Cleared to Lasham" (meaning cleared to change frequency to Lasham). Pilot interpreted this as "cleared direct track to Lasham).
You've gotta believe it..............