I will be doing just the same when I work full time, that's how it works. Society also needs educated people, and obviously while they are studying full time they are not capable of paying the same taxes and prices for public transport.
Considering I will be a doctor upon completion of my university studies, I think society will benefit from their taxes helping pay for my travel concession. It's not about being more valuable, the unemployed also receive travel concessions, it's a reflection of capability to pay full fare, generally. (obviously different for the rich students)
edit: and no where did I say "fucking tradesman", you gronk, lol