Originally Posted by chephy
What's the logic behind allowing one on the road but not the other?
You're thinking about it back-wards. Its not that some things (e.g. electric-assist bikes) are specifically banned; rather, anything NOT defined as allowed is the HTA is banned. To allow a new class of vehicle on the road it must be specifically added to the HTA.
As to why it took so long, hey, this is the government!