Working out if you have to pay super

Generally, if you pay an employee $450 or more (before tax) in a calendar month, you have to pay them super guarantee (SG) on top of their wages.

Ref: https://www.ato.gov.au/business/super-for-employers/working-out-if-you-have-to-pay-super/

What do casual employees get?

Casual employees are entitled to:
a higher pay rate than equivalent full-time or part-time employees. This is called a 'casual loading' and is paid because they don't get benefits such as sick or annual leave.

Ref: https://www.fairwork.gov.au/employee-entitlements/types-of-employees/casual-part-time-and-full-time/casual-employees

Example:

An employee works on a casual basis as a bartender for two separate entities during the week and is paid on an hourly basis. Both employers should use this tax table  to calculate withholding from payments made for the hours worked.

Tax table for daily and casual workers at the link below.

https://www.ato.gov.au/uploadedFiles/Content/MEI/downloads/Daily-casual-workers-tax-table-from-1-July-2018.pdf