Pretty sure no one would. You'll only manage to get unemployed people. Who will bail if they get a full time offer during that three months.

I would. Why? Because I'm confident that they won't want to get rid of me at the end of that 3 month period. Hiring is expensive, and unless I mess up badly, there's no incentive for them to fire me. If they wanted someone temporary, why would they not just advertise for a contractor?

I wonder how much you'd have to pay someone in severance to make it worth it. If there's typically a 20% yearly salary piece for a recruiter, paying 10% direct to the employee in severance if their 3 months doesn't work out might make it work for a subset of people.

You know that all jobs have a probation period even more so in the UK.

Then why bother with the song and dance?