Poor pay rates for early childhood educators is the key reason for the continued exodus from the sector, a royal commission has been told.
United Workers Union executive director of early learning Helen Gibbons said pay wasn't the only issue driving the loss of more than 30 per cent of staff each year, but it remained the most important.
"It's not just about being able to pay their bills, it's also about how they feel valued by the community," Ms Gibbons told South Australia's Royal Commission into Early Childhood Education and Care on Tuesday.
"How much you're paid is a really concrete expression of how much the community values the work that you do.
"I really want to stress that that is the key driver, absolutely the number one issue. Our educators tell us very clearly that if you don't fix that, you don't fix the sector."
Ms Gibbons said other issues raised in a recent survey of staff included the workload on early educators and a lack of support in their roles, both of which led to a sense of frustration.
"They knew what quality early education was and they really wanted to deliver it for Australia's families but really struggled to be able to do so in an environment where they felt isolated, where they felt undervalued, and where their workload was overwhelming," she said.
The royal commission was told the early education sector continued to grapple with an enormous shortage of workers, especially since the COVID-19 pandemic. Many left the profession, citing burnout and mental health issues, after continuing to work during the global health emergency.
That situation was set to be exacerbated by looming pay increases in the aged care sector which could lure away more staff.
Ms Gibbons said there was no evidence to suggest workers who had left the early education sector were returning.
"The people that left at the end of COVID, we haven't seen them come back," she said.
"We have for years said we have a leaky bucket. We keep attracting people to the sector but leaders keep leaking out the bottom.
"I think the holes in that leaky bucket have gotten larger and we've lost even more."
The availability of staff will be a key issue after commissioner Julia Gillard recently recommended universal preschool be extended to all South Australian three-year-olds through a program to begin in 2026 and be fully implemented by 2032.
Her interim report found between 1497 and 2180 more staff would be needed, including teachers, educators and directors.
In other evidence on Tuesday, the commission was told of the ongoing debate over whether a new, and potentially shorter, degree should be offered for those wanting to teach children aged up to age five.
Professor Anne-Marie Morgan, from the University of South Australia, backed the idea, arguing it was "really timely" to have a birth-to-five qualification to meet a growing need and to better focus on those early years.
