Good suggestion they offer their services through chats but if a particular bounty manager asks for this, the project developer will just hire another bounty managers who will not ask these conditions but if they will unite and make this as a condition that will be good for all the managers reputation and for bounty hunters as well.
You should read what @btcltcdigger has said.
Since the third world countries have a cheap wage compared to other countries bounty managers face a similar problem because both are competing for the same job. While someone asks an amount in return for a spam free and well managed campaign another one asks for lower fee but similarly well managed campaign. This leads to a professional jousting and thus is bad for the overall system of bounty manager, project owners and bounty hunters.
As long as the hunters accept that participating in a bounty does not guarantee a payment and follow that mentality they should be fine, if they tend to become very sad on being denied payment, they should look for other earning methods.