Why are ISIS brides being put in refugee camps instead of prison or death?

Because killing them without trial would be murder, there is no death penalty in the EU, and because of misguided populism, the governments are refusing to let them back into their home country and put them on trial, going so far as to retardedly revoking their citizenships.

What do you mean by “ISIS brides”?

I find the very question reprehensible. It makes stretches, and assumptions that are dangerously vague.

I would opine that the OP has vastly oversimplified a very complex issue.

I guess it would have to be a case by case basis. If we assume an “ISIS bride” is someone that was not originally in ISIS and was indoctrinated and married an ISIS fighter, then you have several issues in play if/when they decide to try leaving that life. Was she actually a fighter? Did she commit crimes? Was she a violent threat? Was she participating in illegal activities for ISIS that did not involve actual physical actions? If the bride lost her husband and had done nothing wrong and realized she didn’t like ISIS, she could try getting out. There would be no reason to put her in prison since she had not committed any crimes. However, due to ISIS having a past history of planting operatives to be activated later, many places are leery of just accepting ex-ISIS members as immigrants, treating them as refugees instead.