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 was essentially what Google to engineers when I worked there. They worked for generally just under a year, got reviewed, and then if they didn't measure up to the "level" that they had hired in at, they let them go. They were somewhat up front about it if you pressed them. But I didn't meet anyone there who particularly appreciated it when others would hire them and not do the whole 'check in a year' thing.