One in four WA workers does not get paid leave, the State's main union body has said.
UnionsWA has told an inquiry into insecure work that the trend towards casual, fixed-term and subcontract labour meant more people were being denied the benefits of permanent employment.
Secretary Simone McGurk said more than 220,000 workers were not legally entitled to sick pay and annual leave and were constantly worried about job security.
Fluctuating incomes made it difficult to secure credit to buy cars and homes, she said.
Casual, subcontract and short-term contract workers receive higher pay to cover the absence of paid-leave entitlements, but UnionsWA complained this was not an adequate trade-off.
Companies often insisted on casual contracts because it was deemed easier to cut or build staff numbers in line with changing demand for business, the body said.
"Some employers see it as a way to subcontract out certain industrial relations and management issues, but it is a short-sighted way to manage a business," Ms McGurk said. "Stability allows companies to suitably train their workforce."
Ms McGurk rejected claims from the business sector that changing laws to make it easier to sack underperforming workers, as was the case in the WorkChoices era, would encourage permanency. She said current laws allowed dismissals when necessary while also adequately protecting workers.
The Community and Public Sector Union told the inquiry that the State Government also favoured casual staff.
University lecturer Brad Evans said he had had a lot of difficulty securing a loan to buy a home after five years on short-term contracts.
He eventually managed to get a low-documentation loan, which usually carries higher interest.
The inquiry, which was commissioned by the Australian Council of Trade Unions, will hold public hearings in Perth and Karratha next month.