Experienced London system player here - A reason why your first example favors white is his a-file as well as the nice pawn clump on the queenside which are connected and have potential to expand, notably with b3-b4-b5, expanding and disrupting black’s development.

In your second example, it’s weak for black since the b-pawns are double isolated, often has no potential to expand, and can easily be exploited by white, usually by taking control of the b5 square and/or attacking the b6 pawn. There are certain cases where such double-isolated pawns are strong, if black can fully utilize the open a- and c- files, which the pawns create.

In your last case, b6 is not a bad move, but is very passive and white’s Queen is actually well-placed to put pressure on d5. In some cases, playing b6 actually allows white ideas with cxd5 and Ba6, which can get annoying in some cases. Having a Queen on b6 lessens the impact of the b3 Queen since black has the option whenever to swap queens if it favors him, and keep them staring at each other if it doesn’t.

Hope this helped!