Do objects used in food preparation and foods that have no or little chance of being not kosher really need a hechsher?
Please cite sources, if you can.
Here is one agency's list of what doesn't need a hechsher http://www.star-k.org/cons-appr-no-need.htm
this is one answer about why some apparently hechsher free items might need a hechsher http://www.askmoses.com/en/article/144,2095417/Why-do-supervision-agencies-supervise-products-that-do-not-need-a-hechsher.html
this is about things that get into unsupervised food that don't appear on ingredients labels http://www.chabad.org/library/article_cdo/aid/529218/jewish/Do-packaged-frozen-vegetables-require-kosher-certification.htm
and this article also deals with actual problematic ingredients http://www.aish.com/jl/m/mm/Isnt_Water_Kosher.html
this one discusses relying on ingredients lists http://www.ok.org/Content.asp?ID=116
I know that the OU put out an article about processing and the mashgiach's familiarity with more than just superficial ingredients but I can't find it.