I got the odd free trip from Shirehampton back in the day. We'll, until I got to the gateline at Bristol TM▸ . Then the freeness was time of day dependent. Unless I was bailing at Clifton Down, Redland, Stapleton Road... if so, then FGW▸ /GWR▸ were very kind to offer regular complimentary travel.
I have heard staff asking for anyone wanting tickets beyond Temple Meads, which is a good idea. Better to get those tickets sold first, then the £2 and £3 customers who can pay on the way out. I once saw someone get on at Redland (before 2008) and ask for two first class returns to Dover, to the delight of the TM, who must have been on commission.