I agree with you in that, 20k$ is quite small allocation for the Bounty as per as huge number of participants But I think if they will offer 20k$ worth token and listed in good exchange also have liquidity, i think it's obviously better than high allocated shit project. To get decent rewards BM can run for limited people.
Actually the allocation of $20K would not be too small if the bounty Manager made a limit for each participant and did not distribute the allocation into many campaigns, so that the participants who wanted to participate in it also saw it very clearly that the allocation was very suitable for the number of participants who few and also not many campaigns in it.
You're right, In such allocation bounty hunters can get handsome amount of rewards undoubtedly, If Team and Bounty Manager planning to pick the real hunters in their promotion. But i see few BM didn’t made the rules that's why most of the time hunters got payment and end of the day transaction fee is more than Bounty payment.