It cannot go on as it is now
The current system is completely full of holes and an invitation for fraudsters.
Needs a change, urgently.
Pay per build ensures that there are no more scammers, if it means that future developers have to bring some capital with them (from the start) is even another reason that the whole project runs honestly because once the developer puts his hard-earned money to start a project, he will handle his work more responsibly.
By having a sword of Damocles over his head he will make sure that he often releases updates & keep lying will be punished with sanctions.
Another option would be: An advance payment with consumer protection (similar to PayPal's buyer protection)
Supporters could send money in advance and if the dev will not release a update in an certain time frame, you can withdraw the money.
Or a middle ground:
You could do the whole thing like this, for example, initially it is billed monthly and if about three times the developer is releasing very slowly or not at all, his account is penalized (strikes) & from then on he is only allowed to debit per build.
This method won't completely eliminate fraud, still it will force it out a lot.