Say a person used to require a visa for the UK and was once refused. Now they've become a visa-free national, but was detained for a long time upon a visa-free entry. The only way to nullify the refusal and prevent this from happening in the future is to obtain a visa (a phenomenon unique to the UK).
I wonder: should the person apply for a visa for every future UK visit in their life, or does a single visa approval permanently eliminate the flag caused by the original refusal, so that once the visa expires, applying for visa-free entry won't cause complications specifically due to the original refusal?