As the new hire, I strongly prefer it for the exact reason you state: it's pretty hard to know if I'm a good fit in a company prior to actually working there. I've used the probationary period twice to get out of such mistakes.
As the hiring company, it's also a great thing for exactly the same reason but from the other side of the equation.
Lots of companies do this. I think more companies should join the bandwagon.
The consequences are always about your next job and whether you can explain leaving a position quickly
For the two times that I've opted not to stay, I just don't list those companies in my work history at all. I've never been asked about them in an interview and have never had to explain.
If I were to be asked, though, I'd just say something like "I decided that I wasn't a great fit and left during the trial period so that the company had the best chance of finding a more suitable candidate in a timely way."
however i'm used to not quitting one job until i have the next one lined up (especially now that the interview process can take months to go from application to start date).
Well, that certainly affects your flexibility with this sort of thing. Many years ago, I learned that this stance is too limiting for me and sometimes encouraged me to take jobs that I shouldn't have taken.
Everyone is different, of course, but what works for me is to keep enough of a bankroll on hand that I can go at least 6 months without an income (Although these days I keep 1-2 years worth). That gives me the breathing room to be pickier about where I work.
I have been fooled by companies selling other perks of the company, but the actual day-to-day was terrible because of terrible code.
I've also been sold on intentions to improve the code, but which never panned out after 6 months because shipping features was still the foreseeable priority. You can sometimes find honesty up front like "we know it sucks but we're going to improve it" but that goes back to selling intentions with no real solid date for that effort. It might work out, but it's a gamble for a candidate.
Plus you also get to see incidents, how they write tickets, and sprint volatility and how much stuff gets pulled in/pushed out because priorities change rapidly (there's probably a proper PM term but I can't be arsed).
It would stop a lot of people joining, realizing it sucks, then doing their year and getting something else. Then they might actually have to improve their shit instead of burying the facts.
My current job was contract-to-hire. Officially an 18 month period, but they converted me to employee after 3 months.
How it helps the candidate is exactly the same as how it helps the company: The interview process was a half hour phone screen, a 1-2 hour onsite with two people from the team, and a half hour followup call with the hiring manager who hadn't been able to join the onsite.
You know those week-long all-day interview processes many of us hate? Not necessary at all if the company is willing to give people a try and just move on if it doesn't work out.
You know how companies complain that they can't find good hires because their ridiculous interview process filters out the good ones and keeps the great ones from even applying? Having a sane short interview with probationary hire costs way less productive time and gets people onboard fast. And if someone doesn't work out, you can have another candidate take their place next week. It doesn't need to take months.
This is “try before you buy” for the employer but much, much less so for the employee.
That sounds like a ridiculous interview process which would filter me out from even applying. I'm not going to give up the job I already have and go through all the hassle that comes with a job change for the possibility of a new position.