Amazon's mobile app automatically applies a Prime filter to search results, so non-Prime (typically FBM) listings can lose impression share among the over-70% of buyers shopping on mobile, with no obvious signal to the seller that this filtering is the cause of a traffic drop. Separately, the Prime badge carries a trust effect: many buyers interpret it as meaning "they are buying your product from Amazon" itself, lending credibility beyond just fast shipping.
Apply: Treat loss of the Prime badge as an invisible mobile-visibility tax, not just a shipping-speed signal — a listing can look fine in aggregate metrics while quietly losing the majority-mobile audience. Obtaining the badge (via FBA, since SFP is discouraged) is framed as lifting conversion 5–10%. Related to the buy-box-specific advantage in Featured Offer (Buy Box) Eligibility Rules Favoring FBA and the general case in FBA vs. FBM (Fulfillment Model Split).