Earlier quoted context omitted.
That's an interesting chain of logic. The mere responsibility of a job gives you powers of arrest? Why are there police in the US at all, if private citizens may so easily be empowered?
No, actually in this specific case the law specifically gives ticket inspectors the power of arrest as I said in a comment either up there ^^^ or down there VVVV. But actually in most common-law jurisdictions, citizens do have arrest powers, which is why we have the term "Citizen's arrest": http://en.wikipedia.org/wiki/Citizen%27s_arrest Which (if you look up the bit about Victoria) would probably apply in this case…
With very limited non sworn powers.
"... To deprive a person of their liberty is a serious matter. Authorised officers should only consider arrest as a last resort and when contemplating doing so, consistent with arrest powers under the Transport Act. The following guidelines must be followed. Persons will only be arrested under Section 219 of the Transport Act 1983 as a last resort. Specifically an authorised officer must believe on reasonable grounds that a person has committed an offence against the Transport Act 1983 or any regulation made under that Act and arrest is necessary for one or more of the following reasons: ..."
but the act also warns
"... If an arrest is made outside the strict requirements of this section of the Act, an officer carrying out the arrest may be liable to civil and/or criminal action ..."
[0] CODE OF CONDUCT FOR PUBLIC TRANSPORT AUTHORISED OFFICERS ~ http://www.transport.vic.gov.au/doi/internet/transport.nsf/h...