When running as a game master you don’t want to be strict all the time, sometimes you would allow people to have possessions that they didn’t write on their character sheet, for the sake of probability, and the sense of the game. People are in a market city, a player would like his character to eat an apple, but didn’t write an apple on his sheet, for the sake of the game flow, instead of playing that he goes to the market stand and buy an apple, you allow him to have an apple in his bag, or he might be on a ship where there is a lot of rope, he don’t need to have rope on his sheet to tie someone up.
This keeps the game flowing without unnecessary breaks in the play. I think a good game master should do this.
But then he should be clear that when in certain situations they enter “dungeon mode”, where there is no chances to get gear. This happens when the players leaves the city, or the caravan with no other way to acquire items. Let the players handle their economy, buy the items they need and before they leave the civilization you will inform that this will be the last time in a long time to get geared up. So try to plan ahead.
This will make the game more exiting when in dungeons and actually will remove all “it would be logical for my character to have this item!” discussions. And with time, the players will stock up on rations, rope, torches and other items.
See the guide to must have dungeon gear, for inspirations about what to bring in to the unforgiven darkness.