Couple of situations, just dealt with one.  

About a year ago had someone walk through our property, set off motion alarms at 2 am, had great camera pictures.  Talked with the Police, they said that was not Trespassing.  We have a 6-foot fence all around.

Recently a couple had an argument.  She rented a unit and he rented a few units.  Back and forth issues.  We were out of the country but could see on our cameras.  She brought a trailer load of stuff and tossed it in the driveway in front of his units.  She had already moved out and was not a tenant.  Called her and told her to pick it up. Said no, it was his.  Told her, his location was inside the unit, the driveway was us.  Had to pay our helper to go clean up.

When we got back went to City Hall to do a Restraining order.  They said you have to do at the County Courthouse.  Went to do a Restraining order.  They showed me a list of six Relationships, which were all personal relationships which didn't fit.  I asked what do we do?  They said to do a Trespass with the Police.  Went to the Police and filed a No Trespass order.  So, I asked if she comes back, you can charge her with Trespassing????  Officer says No.  They have to hand deliver the notice to her, before she can be charged with Trespass.

She just came today and told her to get off the property and I called the police.  Said she just got a Court Order to get her stuff.  Didn't show it.  An Officer finally gave her the Trespass notice.  The Court Order requires law enforcement presence.  Which she knew, she just wanted to Try the key.    

Sure, this is not the same in each legal district.  Took a lot more effort than I thought.