Alison, i think you may have misread what I said. I'm in agreement with you.
Mayor, without meaning to go completely offtopic consent in cases of theft is very different. Theft is usually done by people unknown to the victim. Chances are the person who breaks into my home and steals my phone will not be known to me.
So it's going to be hard to convince a magistrate or juror that I willingly gave my phone away to a random stranger. They may as well go with the 'i bought it off a man in the pub' defence.
However, let's say the accused was say my exGF and she claimed I'd given it to her as a present, the only way the prosecution could then prove theft is by supporting evidence such as fingerprints, CCTV etc.
It is the same principle and in theory the burden of proof is to the same high standards. That said, we're all human and chances are there's a lot higher burden of proof required to send someone to prison for rape than nicking a mobile phone.