Why BOA can't cash third party check?

My uncle got his work check. But, he lost his ID. Because of his messed up birth certificate @ court house. He have to go through changes to get his ID. He got his work check as well as workers comp. check that he want me to cash on my account. I went to my bank which is BOA. They said "No" on third party checks cashing. But, I went to BOA atm, slide my uncle check in the atm. The checks clears the next day. They I go to BOA (the next day after it clears) to withdraw it. All this turn around with BOA & banks. I could have deposit my uncle check with the teller the first time. But, question is, Why do BOA accept third party deposits at atm (I did not endorse it. My uncle just wrote his name on back of check)? But, not cash or deposit third party checks at the teller? Crazy I think! A lot of running around.