Re: I'll keep my receipt thanks.
"They can make a citizens arrest or they can just call the police and you walking off it makes you look guilty. In real life they will just detain you till the police get there then whose job is it to arrest said store guard for false imprisonment?"
What you've missed here is the following:
The police have power to arrest someone on suspicion of committing an offence, even if an offence hasn't been committed; i.e. "I think there may have been an offence, and I think you may have committed it."
Everyone else has to *know* that an offence has been committed, and then may arrest someone they suspect of committing it. Triggering a security scanner is not an offence. Unless they *know* that something has been stolen, they *cannot* arrest you. If they try it, then *they* have committed at least one offence.
"This is how the law works in practise, the innocent till guilty part doesn't come into play until you get to court. The police aren't going to assume you are innocent as it's literally their job to catch criminals."
Rubbish. The police will not subject themselves to the paperwork, and their own accusations of false arrest, based solely on the word of a doorman. Failure to stop for a security scanner is not an offence; neither is failure to comply with a security guards. It is trivial for the police to establish whether or not a theft is in occurring as soon as they show up; if they cannot, then what on earth are they going to present to the court when they get there?