I don't know... personally I think the risk of accidentally touching partially inserted plug pins is much greater than reaching into a lamp holder. I still have lots of old ungrounded round face plugs and caught myself several times very close to touching the live pins (mostly when I get lazy and try to plug in/unplug stuff single handed).
Especially when sockets are fairly tight you have to use force and get used to pressing one or more fingers against the cae plate and pull out the plug with the others... and that can get you pretty close to live metal!
