It basically seems to come down to whether you think that consent is something obtained by men or something given by women.
So if you recognise that consent is something granted by the person who is penetrated by a penis, then you can see clearly that consent is binary and contingent - it can be withdrawn at any time if you stop wanting it.
But if you imagine that consent is something for a man to obtain so he can have the sex he wants, then you think that times when he can't be sure he has obtained consent constitute a grey area.
Because the important thing from that perspective is whether the man can go ahead with his intended penetration.
Not whether the woman (or man) actually wants it, but whether it is allowable.
Further along that path are the people whose concern around consent is what can be proven.
So they think a rape didn't take place, even if there was no consent, unless it can be proven in court.
These are the people who are always on about false accusations, because they imagine that an allegation of rape becomes a false allegation if it cannot be proven.
The Sex on Trial was interesting on this.
First they had the young people meet two people with experience of rape
1 a woman who had been sexually assaulted
2 a man who (claimed he) had been falsely accused of rape
It was a very questionable editorial decision to line these two up as equivalents - it implied that women will experience rape as victims and men will also experience it as victims, of false allegations.
When the reality is that men are much more likely to experience rape as people charged with rapes they did actually do.
And women are far more likely to be raped than the men who rape them are to ever face any consequences at all.
The man who chose to come on to publicise the supposed falsehood of his being charged with both rape and kidnap, made a big deal of how he now records "consent".
So after everything that happened to him, he still has no grasp of consent. Recording someone saying they are comfortable with what is happening doesn't constitute consent.
It might, however, constitute evidence in a rape trial.
It really makes you wonder what he's planning to do after the camera's switched off if he's lining up his evidence in advance.