Escrow is a good way to ensure bounty hunters receive reward but it also depend on the project. Take DogData for example had their bounty campaign and did escrow with a bounty management but changed their smart contract few days before IEO making the tokens useless for hunters and when they finally send tradable tokens months later, the whole campaign token is worth $20. If a project team has no remorse or even conscience to appreciate hunters and pay for the effort they took to promote their project. It all depends on the project, if a project is good and honest, even without escrow they will still pay hunters for example Cartesi.