It's all very well if it's a one off, the NTA will never know, but let's say people are willing to pay a premium for your service … because of the car, you're an ex GAA all star or sing Frank Sinatra (how is Tommy?) so you set up a Facebook page and offer your services at a premium, the NTA would soon come across you, book your service and probably bring you to court.
It seems to me that if customers are willing to pay a premium , so long as they know they should be allowed to.
I know a girl doing tours at €30 an hour, technically illegal, she could get screwed some day!