If you aren't getting accepted to a high paid campaign, it is because there are other people who, in the eyes of the manager of said campaign, are making better posts than you and are taking the available slots. If you want to be accepted to a high paid campaign, then you should examine your own posting behaviors and seek to improve them.
How can they know it when not checking my content but denying because of merit, negative trust or anything else but not for content?
Some campaigns have a merit requirements or a trust requirement. This is entirely at the discretion of the manager of said campaign. If you don't like these metrics, then you are free to not apply to campaigns which stipulate said metrics.
This one clearly hasn't so why does he get bashed to implement them? Putting all low ranked members into general suspicion?