You may be able to improve your situation (and help others further).
I'm not clear what's happened - the wording may be significant. Could you please upload an image with identifying details removed?
If you can establish why the case was dropped, you might reduce the fear of it happening again. Evidence of TfL's system failing might be helpful - when you use a bus, you could then just check the light worked and not need to ask the driver. If TfL apologise, you may be in a stronger position for potential future disputes than if this incident hadn't happened.
If the system failed, I would be asking TfL for the solicitor's fees.
Maybe, depending on what the court letter says, a subject access request would help establish what happened in the TfL system.
Even if it was a genuine mistake, that offence would still have been committed if someone didn't pay the fare - the offence is simply non-payment.
https://www.legislation.gov.uk/uksi/1990/1020/regulation/7/made
That makes it more likely something else was the reason for the case being dropped.
Could you please explain why you say that? As this offence is automatic - not involving intent to avoid a fare - it isn't clear why it should have any significant impact on employment. Solicitors may not be good at explaining that (or may, perhaps correctly, think someone is happy to pay to remove the worry even if there's no real risk to their career).