Uh, you do realise that the Oyster card it is not tagged to your name until you register it right?
So there’s no easy way of pointing back to you, unless of course it is matched up with CCTV, which at that point your being tracked for a real non-monetary reason.
As a Londoner the Tube (Underground) and buses are my lifeline to get around the city, I’ve tried to cycle before which on several ocasions almost end very poorly.
I do enjoy the tube, even though it can be sweaty, smelly and sometimes feel a little claustrophobic when someone you would rather not be stuck next to, is next to you.
I don’t use tickets only my Oyster card, I only would ever buy a ticket is when I need to leave the Londonish area.