Within vocational education and training (VET), mathematics learning is often complicated by students' problematic prior mathematics education experiences and associated low confidence and limited prerequisite knowledge. Teachers have insights into students' mathematics learning needs and appropriate curriculum and assessment responses, but their views are often neglected within VET policy contexts. To better understand the challenges of mathematics education within VET programmes in Australia, we focused on three vocational qualifications within a rural VET institution in Victoria, chosen to vary the visibility of mathematics content, learning environment, and curriculum philosophy. Despite this diversity, teachers from each qualification made similar criticisms of the ways their institution implements mathematics curricula. They described how a behaviourist approach to competency-based education (CBE) constrains their capacity to respond to students' needs, with adverse effects on students' mathematics learning. We argue that the assessment and reporting regimes that currently govern education within Australian VET institutions contribute to negative experiences for already disadvantaged mathematics learners. We suggest that the disconnect that teachers described between students' needs and the approach to curriculum and assessment speaks to a larger inconsistency between the social inclusion aims of Australian VET and the way that CBE is implemented.