I think shoplifting can seem different to other crimes. The reason being because shoplifting can been seen as a self induced type of theft. Therefore, the individual is testing him or herself to shoplift 'bigger' and 'better' things'. An individuals adrenalin may increases because they may be caught shoplifting, it also increases the desire to shoplift on a regular basis.
I know it may be boring, but this link below is the official Act, Giving the exact definition of Theft.