There really is no need for a proof, we all know that most of us here don't really have the same "standards" when it comes to sending merit , I sometimes merit posts that make me laugh , I would like to see a single member who sent a few hundreds of merit without having merited a funny-shitty post, I am willing to bet on "none".
The problem with these newbies coming in thinking the merit system is being used by a bot that is always consistent, which is not the case, in fact if you look at suchmoon's topic
Users that you should merit, you will notice that some merit sources haven't sent a single merit to some members who earned over 1000 merit, which indicates that there is some sort of personal preference , 5 people might think your posts deserve to be merited while 10 other people might think your posts are complete trash , some people do post quality posts but members hate them for their shitty attitude - thus they earn way less merit than other members with the same post quality.
I personally don't see anything seriously wrong with how the merit system works ,despite the imperfection, it is doing just fine.
People complain and cry when see laughing posts received merits. They instantly judge that merit senders and receivers are merit abusers. They don't understand that everyone need laugh to have a happy life. Furthermore, no one can rank up with such posts; because if they earn 100 merits in total, and all of those 100 earned merits are come from laughing posts, they will sure be considered as abusers.
Intensity and quantity of those laughing posts and merits earned mixed together to help us judge someone abuse merits or not.
Nowadays, black market of merit or black market of accounts have come to end, due to Trust, Flags, merit system. A bought-legendary account will be caught if apply in bitcoin paid campaign, and with shit-post history, will never get acceptance.