..I think it will make no sense if service providers ask for upfront payment before they can perform their functions to this effect although it will also depend on their terms and if their clients will consent to such agreement if they really exist but ordinarily i think asking for upfront before recovering could trigger suspicion among potential clients, so buddy you are right on all you said, in this kind of function,not is always service before the agreed percentage can be given.
There service relies on if the customer trust them. If the client trust them, any agreement can be done and an upfront payment may be paid subsequently. Because it does not have to do with the clients only, even the service renders can be scammed. If they have to recover the wallet and later on the client refuses to pay the money as agreed, they are at a big lost too. So yeah, and upfront payment doesn't look like a scam hunt, I think it is okay for them to request for it but it shouldn't be more than 30% of the total payment.
Well I really get your point, however this idea of asking for upfront payment is something that I believe is not right especially since the service is in crypto space. So this idea is not okay because so many has used this pattern to scam people. The issue of trust has to come from both sides, if the service provider doesn't trust the people that want to petronise there service I don't think anyone will want to trust them also mutual trust is really important here. It will be a bad I idea to ask someone to for service they are not even sure the company will be able to deliver. Even if they are asking for 30% upfront payment, what do you think will be the fate of those that will petronise them if they disappear?. They should be able to show evidence or a result that they can be able to render this service ,they can start the work then show result of partial recovery. In this way there will be a great trust from there customer.