amazing question dude!
is it bcoz of persistence of vision + rate of emmission of photons from the 2 sources (rate being faster from the light bulb)???
pls say if im right or wrong

ie. bulbs poton emmision rate is lesser than 1/16th of a second magnitude wise(human eye percieves objects in frames of 1/16 of a second)

but, comp & tv screen the rate is more than 1/16th of second magnitudewise (ie. magnitude of fraction)