You don't let children loose on the road without an understanding of how to cross roads, judge car speeds etc. You don't let people loose in cars without some rudimentary training. Why not the same for cyclists?
Regrettably, all the cycle training in the world won't keep the slower cyclist safe if motorized traffic does not also play by the rules.
I dare say not even the faster cyclist is safe.
Show me a way not to be beeped off the road when I cycle in primary - as per cyclecraft suggestion - at 7/8 mph loaded with groceries, uphill on a left filter lane or primary at 15mph on a double carriage lane approaching the junction, again following cyclecraft's advice.
Show me a way not to be passed simultaneously both on the right and on the left when I'm in the correct lane and correct position to go straight.
Show me a way not to have a car on my right and a motorbike on my left in the bike box when I'm in the centre of it.
Apart from the dangers of impatient drivers, getting shouted at or beeped at is not pleasant.
I will continue to illegally ride short stretch of pavement when I feel it's necessary or walking and pushing the bike.
Did I mention, once I got shouted at by a cyclist on a shared path for being in his way