Gryphon is right to be suspicious of the OP's behaviour.
However, that's not the point. Regardless of the OP's behaviour, it's not shoplifting, even if he was being belligerent. Unless the court can prove an element of intent, then regardless of the OP's behaviour, he has committed absolutely no crime. I believe under Taiwanese law, a person must have absolute proof that a crime has been committed before they are able to apprehend somebody. Having reasonable suspicion that an offence has been committed or is about to be committed is not grounds to apprehend somebody unless you happen to be a police officer. Taiwanese law closely follows many aspects of western law in this respect.
The store owner has stopped a person from leaving the store without being absolutely sure that the OP was not going to pay for the goods. I hope the OP made this very clear in his statement and in the prosecutor's initial hearing.
The courts are very nasty in Taiwan, more so towards foreigners and the whole system is extremely corrupt. I would highly recommend seeking legal representation because the prosecutor may well push for deportation for 'not respecting the laws of Taiwan.'
OP: I'm not trying to worry you, but you MUST MUST MUST find legal representation. Get the CCTV tapes. Get all the evidence which supports you defence. Make sure the police emptied your pockets and recorded all the money that you had on you - if they didn't, they weren't doing their jobs.
The courts need to prove intent and you must have left the shop. If they can't prove intent and you didn't leave the shop, then they have no case, but it won't stop them from sentencing you if you do not know the law or have nobody to represent you.
You may get the chance to settle out of court. This will normally involve mediation and paying compensation to the owner and will not normally involve receiving a criminal record. As it is possible that this is what the owner is after (I doubt that justice heads the top of her priorities) then it may well be better to say sorry and cough up depending on the amount. If you are innocent, then it is a hard thing to do, but it will stop further complications for you - and let's face it, I doubt justice heads the top of the court's priorities either.
However, I am no lawyer and no expert. The laws may have changed since I was last made aware of them, which is why you need to seek legal representation.
Make sure the police also have the empty potato chip bag and the till receipt roll as exhibits. Again. if they don't have these items, it counts towards your defence.