(a) That's wrong. Section 18 of the ACL strictly prohibits conduct that is likely to mislead. It is not necessary to show that the conduct was engaged in deliberately or carelessly, although the existence of intention may be relevant to establishing that the conduct was misleading.
When conduct is found to be misleading, liability may exist even if the conduct was engaged in without carelessness or intent. Section 18 is breached even if the conduct took place by mistake, or innocently. This often makes it easier for a plaintiff to prove misleading conduct than, for example, to rely on the common law doctrines of fraudulent or negligent misrepresentation.
Liability for potentially misleading conduct can be avoided if the person engaging in the conduct makes it clear that the conduct should not be relied on, for example, by issuing a disclaimer.
The remedies available for a contravention of s 18 include injunctions; damages; compensation orders; non-punitive orders; and other orders. A contravention of s 18 does not incur fines or civil pecuniary penalties.