Towing Issues: At what point should a drop fee be charged?, tow truck driver, eagle scout

Question
My son is at a university in Illinois. He is a good kid (eagle scout) with no previous issues with police.   He went to a party as a designated driver.  He unknowingly parked in a restricted area (no parking after 11pm) He came out and found a parking ticket on his car marked 11:05pm.  He returned to the party to get his friends and leave. (The police officer saw him do this and assumed that he was ignoring the ticket and called for a tow.  My son noticed the tow truck pull up and ran to move his car.  He got two blocks away when he was pulled over by city police and charged with theft of service (ticket issued at 11:15). He told the officer that he was not hooked up and thought he was within his rights to leave.  (In Chicago there's an ordinance that allows a driver to leave if they come out with their keys) They took him to the station in handcuffs and booked him and impounded his car.  The tow truck driver said that he was "in the air" when he drove off.  My son says that no part of the truck was on his vehicle or he couldn't have driven off but he thinks the driver was starting to slide something under his car.  

Is it legal/acceptable to tow a car 5 minutes after a ticket has been issued?  This was a residential street.

At what point is a drop fee charged?

Answer
Well from what it sounds like here, it seems that the "drop fee" is also being considered a "show up fee" which in many police contracts is legal... Under "police ordered tows" the rules change from what would be normal for a tow from Private property such as a parking lot.

Police do ticket vehicles and if the area he was parked in was a "no parking zone" after a certain time, I would bet that even before  your son came out, the tow truck was called for and was on its way... That tends to be standard practice, as the officer was writing the tickets...

Now as to "hooked up" or not, I am not sure exactly where this happened but in general terms, if the tow truck is there and any part of the tow truck is touching the vehicle then a "drop fee is allowed"

Some tow trucks are what we call "self loaders" which mean that the operator does not have to get out of the truck to hook up, he can hit a switch or two and hook and lift the vehicle in the time it takes to shift the transmission from Reverse to Drive.

I hope this helps, but specific laws at times are State wide, County or City applicable or even a combination of all of them.