They do this because the job seeker is already invested, and doesn't have the time to ponder well their choice, or speak about this with someone else.

They must choose on the spot, and having already invested time. They'll often accept much lower than they would have otherwise.

For the hirer, it pays off on the long term despite the time they also invest. It's thousands, even sometimes tens of thousands of dollars saved each year.

I also don't apply to jobs that don't show the salary in the posting. But I used to when I was desperate.