Revenue attributed to the visit that earned it, rather than to the page the payment happened on. The campaign that brought somebody in gets the credit for what they spent two pages later, which is the only version of the number worth acting on.
The currency is stamped when the sale happens and never converted. A euro sale is reported in euros beside a dollar sale in dollars. No exchange rate sits between you and your own figures, and no total silently changes because a rate moved.
Heatmaps and recordings on the pages that sell. Product pages and carts are where the money leaks, and a funnel tells you which step loses people without telling you what happened there. Both come out of the same allowance as the analytics rather than a second subscription.
A feedback widget where the doubt is. One question on the product page, the thing a shop almost never asks, because asking has always meant buying a survey tool.
Outbound clicks, downloads and 404s counted without being asked for. A broken link in an email campaign shows up as a page, not as a mystery.