Stock peers: missing the obvious?

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Who at SA decides the peers for a stock? According to SA, GM is not considered a peer of Ford; CVS is not a peer of Rite-Aid; GEO is not a peer of CoreCivic, and Kroger is not a peer of Albertson's. It's as if SA will do anything to avoid the most relevant match and instead select companies in another country or in another line of business. Could someone at SA  please explain?