Language and tone
Australian English is not American English with different spelling. 'Ute', 'rego', 'on-road costs', 'CTP', 'drive-away', the vocabulary matters, and tone matters more. US models default to high-energy American sales register; Australians notice immediately.
Compliance
Spam Act 2003, Privacy Act 1988, ACMA, Australian Consumer Law, state-based dealer licensing. Most US vendors cannot map their consent and disclosure flows onto these regimes without significant customisation.
Workflow assumptions
US-built tools assume US OEM ladder logic, US trade-in tools, US credit infrastructure, US insurance products. Australian dealers spend the first six months unpicking these assumptions.
Support and timezone
Production support from a US east coast vendor lands in Australian deal time at 11pm. For a system that handles every lead, that is not acceptable.