The gap between installed and implemented
Nearly every site we look at has GA4 installed. Very few have it implemented. Installed means the base tag is present and pageviews are arriving. Implemented means the events reflect your actual business, the revenue reconciles to your order system, the funnel steps are defined in the order users experience them, and the whole thing survives a deploy.
The distance between those two states is where most conversion programs quietly fail. Teams spend a year optimizing against a purchase count that is fifteen percent too high because the confirmation page fires on refresh, and nobody catches it because nobody ever reconciled the number against the orders table.
