The EU antitrust ruling
Merchants reasonably ask how long a 20 percent advantage can last. The answer is in the origin: it is not a discount Google chose to offer, it is the shape of a remedy imposed on Google by a competition regulator.
The decision
In June 2017 the European Commission concluded that Google had abused its dominance in general search by giving its own comparison shopping service systematically prominent placement while demoting rival services in results. The fine was 2.42 billion euro. The General Court upheld it in 2021, and the Court of Justice dismissed Google’s final appeal in 2024.
The remedy is the interesting part
A fine on its own would have changed nothing structurally. The Commission required Google to give competing comparison shopping services equal treatment: to let them place Shopping ads on the same surfaces, in the same auctions, on the same terms as Google’s own service. Google implemented this by turning Google Shopping into one CSS among many and opening the programme to certified partners.
Equal treatment is the operative phrase. A CSS partner has neither an advantage nor a handicap in the auction relative to Google Shopping Europe. What creates the merchant’s advantage is how the partners price their side of it.
Where the merchant advantage actually comes from
Google charges CSS partners for the Shopping placements they buy, and partners were historically compensated in a way that let them pass value back to merchants. The practical result, consistent across the market for years, is that bidding through an independent CSS costs a merchant about 20 percent less per click than bidding through Google Shopping Europe.
It is not a promotion any single partner is running, which is why every certified CSS quotes approximately the same figure. That is also the reason the advantage is not a differentiator between partners, and why the article on choosing one is about everything else.
How durable is it
The obligation is a compliance remedy under an upheld decision, not a commercial arrangement Google can withdraw at will. The Digital Markets Act has since layered further self-preferencing obligations on top for designated gatekeepers. The direction of European regulation on this point has been consistent for a decade.
That is not the same as a guarantee. Remedies get revised and implementations change. The sensible position is the one the numbers already justify: the advantage is worth taking now, the cost of taking it is a few minutes and a small subscription, and it is reversible if the ground moves.