AFAICS fare evasion on buses is now undetectable.

But one must own a contactless credit card.

As long as one can in any way get on the bus in the first place ( for
example using a stolen Freedom Pass/child ticket or whatever ), one
can then, when asked for one's ticket by a RPI, show the credit card.

Credit cards can't be read by MOVies so the RPI will have to take your
word for it.