Stubhub

Academics working with StubHub carried out a huge test on hidden fees vs vs upfront fees. Users who weren’t shown fees upfront spent ≈21% more and were 14% more likely to complete a purchase. This research involved several million participants.

News article summarising the findings from the research paper "Price Salience and Product Choice". "StubHub concluded that so-called “drip pricing” [...] resulted in people spending about 21% more."