Because money talks the rest walks. That, and the 'old boy's clubs'. Maxwell has no 'power' in her own right, any power she had came from Epstein. The 'old boys' don't give a shit if she rots in prison for the rest of her life.
I think the actual names in the files are just the first domino in a huge row of dominoes. The first 'domino' gets indicted and will sing like a canary and implicate other people to try to get immunity. And the other dominoes will do the same as they fall. And when it comes to businessmen being named, businesses that do business with them fear they will suffer financially if it's known that they do business with XX person. So they put pressure on for names not to be revealed for fear of damaging or devaluing their own business. It's a big nasty onion with many layers, and each layer that gets peeled back may reveal more and more nastiness.
As far as Andrew, the US isn't going to do anything to him ahead of doing anything to the perpetrators in the US. It would be a long and expensive extradition battle to get him here I think. Since supposedly some of his 'activities' took place in the UK, I think the US will leave the UK to deal with him. Now, should he set foot in the US, all bets are off.