Re: Once upon a time detector vans existed
'As defence you're not even allowed to challenge the "expert" evidence in court or even discuss probabilities.'
As an ex-forensic scientist I've spent many hours in court being challenged*. The closest your statement resembles reality is that no counsel I encountered on either side displayed a knowledge of statistics.
From time to time we encountered defence "experts". They would come into the lab to use our equipment to examine the evidence. A number of times I've had to take an "expert" through the controls of a comparison fluorescence microscope. One "expert", redundant, I believe from some industrial job, would take on cases involving all manner of evidence types; within the lab we had our own specialities and stuck to those.
I left before DNA came into use. I do share some reservations about that. I read the original paper, which depended on matching electrophoresis patterns of DNA fragments shortly after looking into the statistics of matching patterns of damage on shoe prints and suspected that there were assumptions in the pattern matching which hadn't been dealt with. Modern techniques don't depend on this but have now become so sensitive that contamination is a problem and I've read of at least one forensic scientist being in trouble for not taking this into account.
"Signal != Person"
AFAIA it's the householder's responsibility to obtain a TV licence so if the network is within the household it doesn't matter who's using it - providing it can be demonstrated that it wasn't a neighbour attaching themselves to it.
*I've also had the experience of a prosecution barrister trying to get me to put more significance on an item of evidence than I considered that it bore - and eventually being rescued by an objection from the defence.