It’s just as well that they don’t. I never liked the idea of celebrities giving huge donations and then advertising it. Makes me question their real intentions.
Once, a few years ago, a group of nuns had a fire and they needed to refurnish their new convent. They went to the local media asking for donations of used furniture. Well along comes a local furniture store owner, who called the station, to announce that he was donating brand new furniture to the nuns. Of course, he was lauded by the nuns and the TV station saying how wonderful and caring this man was. I saw it as a case of free advertising and self-grandizement. He could have just as easily donated the furniture quietly and not call the TV station to show how good he was. Never bought so much as a lamp from him.
In the interest of fairness, public large donations can also spur many smaller private donations. It all depends on the heart of the donor.