Yes, you should be wary as it refers to the way the pages are bound together (sewn or glued/stappled), not to the cover (which, unless it states "couverture rigide" or "couverture cartonnée" somewhere, is always assumed to be paperback when shopping in french stores).

Camus' La Peste doesn't exist in an American-style hardcover edition. It was published in Gallimard's blanche collection, which is a large paperback collection (of higher quality than what Americans are used to for paperbacks, though).

Actually, you might stop looking for in-print American-style hardcover editions of virtually everything (literature, at least) as this simply doesn't exist for the mass market in French publishing. Mail-order bookclubs and such sometimes have them, but that's about it. Those industrial rigid covers that imitates old fashioned bindings are pretty much an anglo-saxon "thing". The French prefer more supple/lighter bindings.

If you want French classics in bound editions, they cost an arm and a leg. There's no "fair compromise" like Every Man's Library, that imitates the style of an upscale collection like La Pléiade with cheaper materials and craftmanship. In France it's the real deal like la Pléiade or the paperbacks and omnibuses.

Camus is available in La Pléiade, but it's his complete works in four volumes, not individual novels. Pléiade volumes are about 120 US$, IRRC.