Our supermarket has a coupon printer tied to the barcode reader, so if you buy a particular product, it will produce a coupon. A while ago, I bought some almond milk from brand A, and a coupon for brand B came out. This week I used the coupon and bought some brand B almond milk. A coupon for brand A came out.
None of this makes me think that brand A is brand B. It makes me think that A and B are aware of their competition and their target market. They win because they get people to try their products and I win because I have choice and save money.
Applied to the the ad-serving model, if I do a search on A, and I get search results for A accompanied by a responsible* ad for B, I now know I have two choices, A still gets their search placement, and B gets a plug as well. Everybody still wins.
*Responsibility is the key. If B deliberately produces an ad which implies that B is A, or the search engine formats the ad such that it appears as a search result, that's fraudulent and should not be allowed.
So, surprisingly, it looks like the US model is actually sensible on this one.