That's why they're testing irradiation.
New Link:
http://current.com/items/88899709_washing_fruit_and_veg_is_pointless
"This is the first study to look at the use of irradiation on bacteria that
reside inside the inner spaces of a leaf or buried within a biofilm".

http://www.ext.colostate.edu/pubs/columncc/cc000630.html
" Wait until just before preparation to wash or immerse your produce in clean
drinking water.
Buy only what you can use within a few days. Most fresh vegetables can be
stored for two to five days." (not realistic for many). They're also warning
about the produce washers. (Never heard of).

So if irradiation helps keep them safer, longer, I'm all for it, as long it
doesn't drive the price up or delay delivery.
J