Mystery of the missing galeros solved

Cardinal Montini, later Pope Paul VI, playfully displaying his galero upside down

Galeros are tasseled hats cardinals receive from the pope upon being elevated to their new rank.  Originally, a galero was a simple pilgrim's hat, but over time a distinctive color (red) and the tassels were added to indicate the cardinal's rank.  The practice of bestowing galeros upon cardinals began at the First Council of Lyon in 1245, and continued for more than seven centuries, until 1967, when Pope Paul VI abolished the practice, on the grounds that the hats were too elaborate and very few understood why they looked like that.  This is why there are no galeros hanging from the ceiling of St. Patrick's Cathedral for Cardinals Cooke and O'Connor, since neither received a galero from the pope when they became cardinals.

Are cardinals forbidden to have galeros, or could Cardinals Cooke and O'Connor have bought their own galeros and worn them around, or put them aside for hanging from the cathedral ceiling when they died, thereby continuing the edifying practice of demonstrating that worldly glory is passing, even if it passes very slowly?  Yes, they could have, and some cardinals do just that.   Some do a lot more than just wear galeros.  Some even drive around in galero mobiles:

   Cardinal Malcolm Ranjith of Colombo Sri Lanka in his galero mobile

Although the pope no longer distributes galeros to cardinals, everyone from a cardinal down to a monsignor is allowed to display an imaginary galero in his coat of arms, and the Archbishop of Prague and many others do this.

Arms of the the Archbishop of Prague

Bishops generally choose green for the color of their imaginary galero, except in China, where "wearing a green hat" is slang for a cuckold, though why this should bother a bishop is not obvious to me.