I might have handled it differently.
A family shows up, with scouts in uniform, to some event and they haven't paid. That's fine. I think the first thing I would have done was consider how much the pack will go into debt for them paying nothing. Apparently it's about $4/scout, so call it $10. Next, I'd consider the shame and embarrassment on these scouts of being turned away. About the same time I'd ask myself why they didn't pay. That's always tough to figure out. They could be just trying to get a free ride, might just be really disorganized, might be broke and too shy to ask for help,