You really shouldn't be calling people ignorant because you have demonstrated considerable ignorance in this post.
A standard applies to similar situation. In this context, the standard is that charges are warranted when the evidence supports them.
What you don't want to admit (or don't know because the right wing media keeps you ignorant) is that there is evidence to support Trump's charges and not Clinton or Biden.
To charge someone for retention of classified material, you have to prove that it was done intentionally. I don't know much about the investigation into Biden, but it sure as hell seems that is going to be an extremely difficult barrier. That has always been the standard. Classified documents get misplaced. We don't prosecute mistakes. We do prosecute people who we can prove took classified documents knowingly and we definitely prosecute people who take them and then try to hide it from the government.
To charge someone with obstruction of justice, you have to prove they intended to obstruct justice. The FBI could never find evidence that Clinton ordered her tech worker to delete the server after the subpoena was issued. That's just a fact. They interviewed the person who deleted the server, and even gave him immunity in exchange for testimony. He said no one told him to delete the server after the subpoena. There is no email or any other communication that could be used as evidence, so no charges could be brought. Again, these are just facts you are either ignorant of or ignoring intentionally and replacing it with "it's a fact" and calling me ignorant for not participating in your partisan hackery.