Differences between Sephardic vs Askhenazi davening and Selichot

Now that Ashkenazim have started selichot, it got me thinking my Ashkenazim in general just rush through selichot while Sephardim and Yemenites sing parts of it and don’t rush through it. This kind of also applies to regular davening, why do Ashkenazim daven quietly and only read the last couple verses out loud with the exception of some songs (Adon Olam, yigdal, yedid nefesh,etc)