Riding in an urban environment can be intimidating as cyclists must go toe-to-toe with pedestrians, cars, other cylists, the weather, bugs ,wildlife, and road hazzards. I kind of like the challenge, but others on the road might want to eliminate as many obstacles/hazzards as possible.
The greatest hazzard is probably falling over and when I was in NYC recently I spotted what appeared to be a stabilization system to avoid falling over -
Over years I have seen many three wheeled bicycles, but I had never seen an "adult" set of training wheels. I did quick Google search and these appear to be a set of Evo EZ Adjust Training Wheels.
I'm for anything that makes people more comfortable on the roads, and I might just need a set in about 30 or 40 years if I keep up my commuting lifestyle.