Thanks for worrying about my child SteveHall. I'm not quite convinced however that towing the trailer with an e-bike is more dangerous than towing the trailer with my pushbike. Up the hill, on my push bike I am slower than walking speed (literally, pedestrians overtake me). This means I get wobbly which is a source of danger. Also slow starts at traffic lights=danger.
Even with the motor assist, I won't be going up the hill at 15mph. Instead, the motor will help me achieve a 'safe' speed.
Going downhill, I could easily go faster than 15mph no matter if I have a motor or not, but (particularly when towing the trailer) I don't.
I decided 2 years ago that the trailer was safe enough for me, consciously choosing one that has been extensively safety tested rather than a much cheaper alternative. If anything, the e-bike, in my opinion, will make it safer.
And then a big part of it is about riding safely. I choose my routes carefully, taking the long way round if it is safer, another point in which the motor helps me to ride MORE safely. I cross big crossings and roundabouts on foot, meaning the scenario of right turn etc. that you lined out above does not apply - I simply avoid such situations.
Yes I would personally love a Bakfiets, and an electrically assisted one even more... BUT can't afford it. (1700 minimum for basic short bakfiets, plus 1100 for electric assist kit, plus various necessary accessories such as rain tent, seat belts, ... getting close to 3000. And then I wouldn't have a normal bicycle so add another 500 quid or so for that). For that money I could buy a car AND learn to drive.) Instead I have a 700 quid trailer and 500 quid push-bike, and now looking for e-solution.