The syndicates take the strip and sell it to newspapers and split the income with the cartoonists. Syndicates are essentially agents. Now, can you imagine a novelist giving his literary agent the ownership of his characters and all reprint, television, and movie rights before the agent takes the manuscript to a publisher? Obviously, an author would have to be a raving lunatic to agree to such a deal, but virtually every cartoonist does exactly that when a syndicate demands ownership before agreeing to sell the strip to newspapers.