You get people who earn their money and people who try and do as little as possible, such is life.
All I can say is that when the **** hits the fan on the ground, you really value a good signaller, it makes the difference. They're worth whatever it is they're getting. When you know everything is going wrong, can hear the alarms etc going off in the background, and you still get a calm, considered response to a telephone call, it's worth it's weight in gold. Having stopped the whole Midland Main Line because a suicidal trespasser was running towards an approaching freight train, it gives an appreciation of the skills required to hold it together and act decisively. - I made the call, the chap received and processed the information I gave him, and everything was made safe in a few moments.
I play at the job in my spare time and even then it can get tough.
As for the likes of the S&T and Pway, I know Network Rail don't tend to do new works themselves, but again, for whatever silly reason I decided it was wise to volunteer to help with some wiring in a relay room (under supervision, of course) - it did hit me at the time that what I was doing was exactly the same job that following a cockup, resulted in the Clapham Junction crash with 30+ people dead.
That's a lot of responsibility on people's shoulders, without the personal risk to their own safety being out on the line, and again I think they earn every penny.