Trams, buses, metro in Prague free for people 65 and older. You must have id or passport with you on the trips just in case you are ask for your ticket to prove you are over 65. Wish we knew this a day ahead could have saved us some tram ticket money. Live and learn.
Is it for everyone? A lot of the European countries allow discounts for seniors but only for their residents. And sometimes you have to have a special card.
Thanks for posting. When we visited Prague in 2019 we took a walking tour with Jason from Living Prague. Jason informed us and we took advantage of this wonderful opportunity!
https://community.ricksteves.com/travel-forum/czech/are-prague-transit-passes-free-for-senior-foreigners
Edited to add: We did carry our Passport with us. That said, we never had to show it.