Maybe it's just a person who doesn't know where to park? I recall a friend of mines having the same issue. She thought it was an ex stalking her, but it turned out to be a visitor of their neighbors who just parked where ever lol.
I'm sure even the dumbest of thieves wouldn't reveal themselves to a potential target. They'd more likely drive by your house stalking for a few days. Learning how many cars are there and knowing when you're gone. Not just deliberately make themselves known.
