I'm a founder of a startup and I would only move someone across the continents after working with him for a while. For example I would fly him over for a month to work for us to see if there's a fit (without asking him to leave everything yet), covering his expenses, flights and anything other expense he would incur.
I understand if the startup is paying for relocating you but you're still taking a big risk, there's always the chance that you would be let go if you're not a good fit.
How other are mitigating this risk? Is working remotely for a couple of weeks/months with occasional flying viable and moving only after you spent some time with the company viable for others here?
They said I would be able to stick around for a few months until I found another job, which they would be sure I would be able to find very quickly in SV. Now I've been working with them for 3 years.
The details were actually written down, so it wasn't an informal contract, but it's been 3 years.
Also remote trial work should be an option for these kinds of workers. Making your company remote worker compatible will force many best practices from the start at your company.
You should always hire the best candidate which you think will work out but that month allow you to set the right phase, this is a month where you both give the best to make that relationship work - orientation, pairing, documentation, short meetings to discuss potential roadblocks or issues.
All startups usually do this - I just consider it's a good practice to say it out loud that there's a period where we both find out if we want to keep working together.
It's important to remember that the "companies prostrating themselves at your front door offering you bonuses and perks and lavishing dining you" is an American Tech Hub phenomenon. While I doubt UK coders are doing badly, I doubt they are as in-demand as they would be in SF or NYC.
That said, I'm "old" (36), and have family responsibilities. If I were a naive recent grad I might have entertained doing this.
Trying out at a company for a month isn't really that bad when the demand is so intense you can literally line up 3-4 competing offers in under a week if things don't work out. There is sadly no place in Canada where the demand is that high.