its clearly harder for cops / nosey citizens to judge if a home built e-bike is "legal" or not if ridden
responsibly but the authorities definitely are becoming increasingly aware that some
manufactured e-bikes are outside legal limits - quite possibly due to competing dealers pointing this out!
monitoring/enforcement of laws relating to
any cyclist (powered or otherwise) varies from region to region and tends to be worse in urban areas/cities... people here in some parts of London are mentioning incidents of cyclists being stopped if they are going across red lights/on pavements.. they do random checks on cyclists in Ipswich but thats mostly against riding on the pavement / not having lights...
TBH a 18-20 mph ebike would probably still go unnoticed as many unpowered cyclists can go over that speed (I regularly used to do so) - but 22-25mph on anything not looking like a "lycras" bike and eyebrows
will be raised.. even in countries where the Pro Connect S is legal I think you need to wear a helmet and have it registered/with 3rd party insurance... some cops definitely do recognise e-bikes as they ride them! I believe a bunch of Wispers are in Police service in Wales, as well as other models.
I can remember when loads of my (younger) mates were getting into those mini motos etc (nearly 10 years ago now

) - they got away with them for a bit (and not
all of them rode irresponsibly) but the cops eventually caught up with them and clamped down. Ditto with mopeds being ridden with illegal mods/on expired CBT etc... all it takes is for enough "concerned citizens" to whinge or for someone to have an unfortunate collision..
I'm still dubious about this whole e-bay auction anyway, its not really the sort of thing someone would buy as a gift on a whim especially as its not even a normal stock item for this country's dealers unlike the other legal Pro connects!