Isolation based on COVID symptoms is helpful and important, but far from perfect.
Contagion can happen before symptoms or without symptoms.
An inaccurate test (say, 30% false negatives) is likely more accurate than isolating based on symptoms.
Cheap quick (15 min) antigen tests accurately detect contagiousness (often 95%+).
Governments should make emergency allowance for antigen tests that are authorised for clinical use to be used at home. They’re easy to use.