Advice please
As per title, driver pulled off the highway into a pub car park for a quick driving break, no other vehicles on the car park and pub was closed. Occupants didn't leave vehicle or vicinity of it just pulled in for a leg stretch and break from driving. A passenger suddenly looked up and noticed the two warning signs in the car park, which were not visible from eye level or whilst parked. A passenger attempted to download the app to pay but signal was not strong, the app did download later but retrospective payments not accepted, and also no payment without location code, which couldn't be seen anywhere. After this the driver left, hoping that the short stay would be within some allowed timescale, obviously not!
This is driver error I assume for not spotting the sneaky signs, is it best to just pay up now?
Photo of car park sign from internet as didn't think to take one at the time.
Any advice appreciated, have already been advised to pay up on another group so occupants are resigned to this being an expensive pit stop.