How would you know that they are who they claim to be?
There is an urban legend in my city that a person claiming to be a parking attendant worked outside the zoo for 20 years, pretending to work for either the local government or the zoo, collecting parking fees from visitors.
Similarly, I was with a friend who parked at the far end of a parking lot that had a McDonalds at the other end. When we came back there was a car boot on the car, I wanted to speak with a general manager to confirm they were "Enforcing the parking lot of McD's customers only", they said we could talk with the shift manager (who they may or may not be working with separately). My friend just wanted his car and paid them without checking anything with a credit card - on their phone+square device (or whatever that portable cc reader is). It was sketchy and I hadn't seen them there before. I am not even sure that is legal tbh, but didn't have time to work through it with him/them.
Wanna know how I know you're at least as old as I am ;)
People use maps on their phone for weather and traffic these days, along for music.
More so, signage is mostly useless. The problem is the world is covered in advertisements so much to the point that we all have our "AdBlock for Brains" coping mechanisms, that commonly lead us to bouncing off a door then realizing it says "use other door" and people asking why we didn't see it when every other square inch of the door is covered it words saying "Buy this addictive drug" or "Eat this sugar filled crap"
Simply put this is a much harder problem to solve then one would expect as we've allowed marketers to buy up all of our attention.
I remember (90's) those blue signs outside of cities or towns along the highway to "tune in for traffic information" on some AM station. These days some cars are being made without AM radio: https://thehill.com/homenews/nexstar_media_wire/4004678-say-...
Then the Parking Attendor would be the person to get the QR code from.