Who is charged with counting each individual stroke administered to every horse throughout each race and can it only be done efficiently by reviewing the video of a race a number of times, especially in large fields?
It's just that if you have a rule set in stone then surely it's important that you do not turn a blind eye to the also rans in a race otherwise that defeats the whole object of the exercise, if it's truly about animal welfare and not just public perception.
I suspect that the BHA does not have the resources or desire to implement this rule to the full and their only concern will be those horses being over-whipped that the public can see, i.e. those leading the field in the closing stages of a race. The others will get off the hook.