I don't think it really has anything to do with age....well, depends on what you mean by youngsters? I'm 19 and no signals really pisses me off, mainly because on the bike it means I loose momentum as it looks like people are going straight over the roundabout. In the car it annoys me too as it seems silly having to stop because some moron can't put a light on....though, it's not as bad.]
Your right! I'm 41 and probably meant "New Inexperienced Drivers - are they told not to signal?" For the same reason as you - loss of momentum whilst cycling /driving.
Thomas, to be honest "older" drivers proportionately cause me more trouble.