I regularly see Ticket Inspectors working on the (Underground) trains I
drive.

You attempt to avoid the correct fare at your own risk, but don't come
crying on here if you get caught - you won't get a lot of sympathy!

I didn't say that I am definitely doing it, I just asked for some
advice whether it works and how risky is it. I travel in the Tube for
2 months and never saw a ticket inspector, so I assumed there aren't
many of them. Or It probably means that I am lucky

It's not really worth getting a Z1234 travelcard, as I spend roughly 5
a day for 5 days, which gives me 25 pounds, nearly 10 less than a
Z1234 travelcard, but 6 more than Z234, not to mention that I have
bigger flexibility.

Also, I just checked - there are no travelcards in DLR ticket machines
(or at least in Bow Church) - only one day travelcards, nothing more
than that.