Its probably cause no matter how mature or grown up you are, your still your parents child, and its difficult to reverse a lifetime of being told what to do.
Backbone do men have them?!

I'm sure they do, sometimes its easier to keep the peace than risk an argument. IMHO Kiwi mean don't like confrontation. They'd rather get out of the way.
Its not only DHs, DW/Ps have a hard time of it too.
I just hope that I don't become the kind of MIL that everyone vents about.