Very good questions! I will now talk about EOS, and how the Block Producers operate there. The witnesses run servers which validate the blockchain transactions. They also must update the code when any changes to the code occur. If they don’t update, with all the others, they will be cut off from the EOS blockchain. Computer programs run the validating of the transactions, and this means that they are not involved in accepting or rejecting transactions…..Witnesses have a lot of other duties too….most of the BP’s create dApps, tools and other software projects for the EOS community, and the community knows about this, knows which ones are doing good work..When a BP does a malicious act, the EOS community will find out about it, and hopefully, will remove their votes for them….some of the issues arise when big power players have too much control…this is a problem that has not been resolved yet.