The funniest bit about this is how I discovered he did this, one day I got up too early thinking I was late, rushed out and drove off without my usual morning routine and when I heard a voice behind me asking if he could please get out of the car, my heart nearly stopped :)
On the plus side: plenty of ventilation ;)
This was around 1989, the location is Veemarkt in Amsterdam ('Veemarkt' is dutch for cattle market).
Back then homeless people in Amsterdam were fairly rare, now there are 100's of them.
One funny angle is that I was living there illegally myself, I didn't have a kitchen or a place to shower there and it being so quiet is why I got away with that. The people from other companies in that building knew that I was staying there overnight, but they in turn also didn't mind because they saw me as their 'free nightwatch', so there is some recurring element in there.
Anyway, it's ages ago, and if it happened today I'm not sure how I would respond, and I always wondered what happened to him but I did not see him after I moved (I went all the way to Poland).
https://www.google.com/maps/@52.3679788,4.9392218,3a,75y,187...
My unit was the one one from the corner on top (the entrance was at the back), about 60 square meters, an early version of a hackerspace I guess, and the bike path on the left wasn't there at the time, that's where there was parking space.
Now there are a few thousand people living on the other side of the street so you would never get away with it today anyway, someone would spot you there before the first day was out.
Someone smashed my window, and someone stole my radio. (I knew the cops wouldn't do anything besides laugh.)
Didn't care about the radio, but that window bothered me.
I decided to keep the doors unlocked, and carried a portable radio to work. (Too cheap to pay for parking.)
I put a sign on the rear window, "Please go ahead and sit in the truck, or sleep in the bed, but Don't Break Anything. Everything is unlocked."
It was an old Toyota, and it had a kill switch hidden.
Never had a problem again.
There were days when I would find cash in the glove box. I don't think it was tip. I think my truck was being used as a drug drop, but didn't care.
That could actually end up getting you in legal trouble, and at the least get your car seized.