Some of these “guards” are absolute nonsense. You could literally be the only car in the parking lot, parked in reverse (meaning getting out doesn’t need help), and they’ll still come to you and guide you out of the parking space. When you don’t pay, some throw tantrums as if their services were asked for. I expect this to be the norm now full time.
If I get out a shop or shopping center and my car is still there and not damaged or broken into, I tip the car guard if I do have cash on me. I won't be using this app though, but have no problem, in principal, if they ensured the safety of my car.
Like the idea, the guards? it depends. The few that always looks out and greet me by name, friendly and is there to assist when needed, I will always go out of my way to pay them something. Those that act like they own the place and demand stuff, I tell the stores and have them removed, they can't be good for business.
The more members of the public write to, or post on a Mall's facebook pages, or website, or contact us email, the MORE the malls will then realize we don't want car guards there. These people won't mind-read your wishes guys. You need to voice your opinion TO THEM, however much work that requires, to make them realise what the general consensus is.