See, there a reason “self-swabbing” is not a thing in my country (France) where tests can only be performed by professionals.
The same reason they actually have to be at least a bit painful.
As U.K. govt can tell you
gov.uk/government/pub…
Because as long as people don’t know they’ll take precautions/not disregard symptoms, even mild.
Whereas a false negative may be lethal for them/their contacts.