That is right, it doesn't cost you anything to upvote but your Voting power. That applies when you have all SP of your own. Bots have a different situation. They are being delegated SP by other users, which they have to pay daily. They lease the SP by investing STEEM. These are the variables that need to be considered. Total vid amount for a day is used to cover these expenses for that day. I hope you understand.
RE: Daily Payout Timing Changed..... | @whalebuilder