I never made the come-back-for-money ending, but I saw vids though.

Not extremely sure, but I think the Pinkertons just set the camp on fire to make sure all the gang's supplies & else are completely destroyed and so therefore, they don't come back.

In terms of aesthetic, it also just adds a little something... visually dramatic :']

For ~aesthetic~

Yeah I didn't go back for the money but I was watching someone play and they did and I was wondering why it was on fire, now that you say it I bet you're right plus yeah it adds to a great stage for Arthur to knife fight the 🐁

Pinkertons set it on fire I guess, not sure why

@Dragonfireball20 the Pinkerton Detective Agency in real life frequently burned places down like buildings, barns, houses, if there were violent criminals hiding inside.