Crematoriums are in use most of the day - they have a schedule and probably after this funeral, anopther was waiting outside. This is not the nanny state - just simple manners - I have taken loads of JW funerals at Crematoria and there is a time slot for the service, and there was always a funeral service to follow of another person and the family for that needs consideration and not leaving in funeral cars waitinf for the previous service to finish - the charge/fine or whatever you want to call it is a simple means to ensure that everyone uses just the time alloted and does not burden a following family with extra wait.
The time to have sat with a coffin is before arriving at the crematorium