In their defence something could happen that might require them to go somewhere at short notice. And you do say the majority rather than all.
You'll know more about it than me but aren't a lot of people using foodbanks in work? Could have been a call with a shift available or something similar. Job interview at short notice? Lot of companies making a pretty penny by exploiting desperate employees.
Could have been something worse. People having a hard time of it aren't always making rational decisions.
Not a criticism btw - good on you for the work you're doing and I hope stuff like that doesn't dishearten you too much.