My experience with these "free" lifetime warranties when offered by car and truck dealers is that the dealer's cost for the warranty is factored into the negotiated price, just not listed as a line item. About 10 years ago some of the same dealers were trying to sell the package separately, often starting as high as $2000 then negotiating down to less than half of that depending on your sales resistance. The "free" lifetime warranty later got combined with "free" lifetime service which, once I bought it, turned out to include only oil changes, and the warranty part of it excluded "wear and tear" items (note that the Longview warranty does not include most of the drive train on motorhomes).
Car dealers today not providing "free" lifetime warranties will often go lower on the sale price.
Thus on RVs you might find the same unit a few hundred dollars cheaper at a dealer that offers no "free" warranty, and in any case you will likely be buying more service, inspections particularly, that you would otherwise.