Voting is recorded on the blockchain. So there’s a fee for voting in the current version, which doesn’t make sense to pay a fee for 1 upvote.
In the Mainnet, we will move upvote records from the smart contract because it is not very optimal to pay fees for upvotes. I’m planning to move voting records to a public database which will be fee-free. Only in that case the problem you say occur. And as a solution, we can have “verified accounts” who will have access to voting and answering questions. Verified accounts will have to pay a one-time-fee to be able to earn bounties.