Legitimate company with questionable policies and no customer protections. Something goes wrong, you're on your own.

I think it is legit but I think they are run dishonestly like a scam.
They will not assist you if something goes wrong. They side on the side of the Poster - because that's who' earning them money - even when they have evidence that there has been a problem.
If there is a dispute, it won't be decided on the evidence and you are not given any right of appeal once they make a decision. This is the problem with paying upfront - if there is a problem with the quality of the work and/or the behaviour of the Poster you have no support and no recourse to fairness.
Don't use Airtasker