And there is, in fact, a physical document which shows all of this in one place, which your accountants are accustomed to working with, and which is a paper trail that they can go back to if there is ever a question (or an audit) later – your receipt.
Without it, you’re making more work for them – they have to find you, find the widget, dig back up the email where you said you were buying a widget, go to the online store site (where it may not, in fact, any longer be $29.95). And, if they need to go back and examine the purchase weeks, even months, later, your “look, here’s the widget, here’s the web site” method is even less valid.
As others have said, the issue is that fraud in companies is pretty damned common, and documentation rules are in place to minimize that fraud. No, one $29.95 expenditure is not going to break a company (and, as has been said, some companies have policies in which they don’t worry about receipts for small purchases), but other companies (probably particularly those which have had fraud issues) are draconian about it, because they’ve adopted a zero-tolerance / zero-exception policy.
Depending on how and why your company is undergoing an audit, it might be a third-party accounting firm, or it might be the IRS. In an audit, the general idea is that they’re examining the company’s financial records closely, to make sure that there aren’t any irregularities.
And, again, one small missing receipt is probably not the issue – it’s if there are a lot of missing receipts, or if receipts for larger purchases are missing. If a company plays fast and loose with its documentation, they’re simply opening themselves up to possible issues down the road (and your accountants were trained to not operate that way).
