That actually in rules. You can pass through allied unite space, as long as you not end your movement in the same space.
You can, but IIRC I think that it counts as difficult terrain (half-speed) due to squeezing.
That said, yeah agreed that this needs to change a couple of times I have ended up with my entire party stuck behind whichever of them rolled last in initiative due to them being first through a doorway.
