Re: 50 cases in the last 25 years
"The statistics which show actual voter fraud by voters trying to vote multiple times is effectively zero?"
The statistics show there are around half a dozen convictions or cautions for "Personation/legal incapacity to vote/multiple voting" per year. Relative to the size of the electorate, that's an order of magnitude more than the claimed level for the USA. Are American voters so much more honest, or are American elections so much more resistant to fraud?
Read the Electoral Commission's example summaries of the convictions/cautions. The impersonation/multiple voting cases are all detected by polling station staff who happened to recognise someone who had already been in earlier in the day. If that's what you're relying on, then it's pretty clear you're only catching a fraction of the people who are using someone else's vote. If Britain is only catching a fraction of fraudulent voters, then the USA, with apparently a 15x lower level of fraud, is definitely not detecting all cases. And frankly none of us have any idea how many cases are not being detected.