Apparently lots of vaccination sites were indeed different.
Your food bank analogy would work if they were serving fresh food and could not give it all away, so invited any and all to come and eat. Which was the situation at many vaccination sites. Doses were going to waste if people did not use them. And when not enough people in the designated groups were showing up or making appointments at some sites, everyone was encouraged to come so the shots did not go to waste. That so many showed up after the general call for people is a marker of success. Not the one intended for initially, but better than shots going to waste.
Your food bank analogy would work if they were serving fresh food and could not give it all away, so invited any and all to come and eat. Which was the situation at many vaccination sites. Doses were going to waste if people did not use them. And when not enough people in the designated groups were showing up or making appointments at some sites, everyone was encouraged to come so the shots did not go to waste. That so many showed up after the general call for people is a marker of success. Not the one intended for initially, but better than shots going to waste.