That does seem rather odd. So what if folks offered a salary but also made it strictly probationary up front. Sort of "You are going to be evaluated after 6 months/a year on the job and if you don't meet our expectations you are out." ?

This is exactly how it works here in Australia, for graduate and "normal" positions alike.

3 months probation with minimal notice, option to extend to 6 (but no greater due to workplace regs). Works well and means the employer doesn't have to take you on as a "casual" just to avoid the risk that you might be shit.