They may have all gone into work after they couldn't get a test, which is probably what most people will do in practice,
if they don't have full pay, an understanding boss and no problem isolating for days
Many would just shrug and give up after this set of responses:
"She phoned her GP, they said they have run out of tests."
"We are not a test centre, go home."
"We only do antibody tests I’m afraid."
It can also be much more difficult for those who don't have a car, like the daughter, since they won't want to take a taxi