Section 463 is titled "Travel, Entertainment, Gift, and Car Expenses". So when it says "Your expense, other than lodging, is less than $75." what it's really means is "Your travel, entertainment, gift, and car expenses, other than lodging, that are less than $75.
Section 463 does cover many business expenses, but it does not cover things like: Inventory, Supplies & Materials, Cost of Goods Sold, etc. Those types of things DO always need receipts-- not for bookkeeping, but for audit protection in case the IRS decides to haunt you.
For instance, if you operate a taco truck, you don't have to keep receipts (under $75) for pumping gas in the truck, but you do need to keep receipts for the ground beef, cheese, taco shells, pots, pans, skillets, serving containers, etc. regardless of the price. For purchases of items that are out of the norm or not obviously business related, jotting a note down on the receipt can also come in handy if you ever get audited.
The IRS wants proof, not just that you spent the money, but that it was ACTUALLY for the business. Back to that example... If you buy the ingredients for your taco truck from your local grocery store, the IRS will want to see the receipt that says you bought beef, chicken, cheese, and taco shells, because without that they'll say you could have just as well bought apples, Oreos, and Cinnamon Toast Crunch for your family which obviously isn't tax deductible. They'll always err on the side of giving you as little as possible-- so keep those receipts!
