The Ronald McDonald thing - as well as Shriners actually started because of the heartbreak the rumor caused. People spent tons of effort and time based on the rumor only to find out the tabs were worth no more than the scrap. Ronald McDonald and Shriners don't get any more for them then scrap weight but wanted to provide an outlet to accept those donations to lesson the blow of finding out it was just a rumor.
Edit:
Found this link